diff --git a/test/fixtures/wpt/README.md b/test/fixtures/wpt/README.md
index 337944bf9c1c72..2129ee15c5b8a8 100644
--- a/test/fixtures/wpt/README.md
+++ b/test/fixtures/wpt/README.md
@@ -27,7 +27,7 @@ Last update:
 - performance-timeline: https://github.com/web-platform-tests/wpt/tree/94caab7038/performance-timeline
 - resource-timing: https://github.com/web-platform-tests/wpt/tree/22d38586d0/resource-timing
 - resources: https://github.com/web-platform-tests/wpt/tree/6a2f322376/resources
-- streams: https://github.com/web-platform-tests/wpt/tree/bc9dcbbf1a/streams
+- streams: https://github.com/web-platform-tests/wpt/tree/f8f26a372f/streams
 - url: https://github.com/web-platform-tests/wpt/tree/7a3645b79a/url
 - urlpattern: https://github.com/web-platform-tests/wpt/tree/f07c03cbed/urlpattern
 - user-timing: https://github.com/web-platform-tests/wpt/tree/5ae85bf826/user-timing
diff --git a/test/fixtures/wpt/streams/META.yml b/test/fixtures/wpt/streams/META.yml
index 1259a55cb5a99e..a16a3c47a03559 100644
--- a/test/fixtures/wpt/streams/META.yml
+++ b/test/fixtures/wpt/streams/META.yml
@@ -1,7 +1,6 @@
 spec: https://streams.spec.whatwg.org/
 suggested_reviewers:
-  - domenic
-  - yutakahirano
   - youennf
   - wanderview
   - ricea
+  - MattiasBuelens
diff --git a/test/fixtures/wpt/streams/WEB_FEATURES.yml b/test/fixtures/wpt/streams/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..d10bbe4a7d7012
--- /dev/null
+++ b/test/fixtures/wpt/streams/WEB_FEATURES.yml
@@ -0,0 +1,5 @@
+features:
+- name: streams
+  files:
+    # Top-level only. Subdirectories have their own mapping.
+    - "*"
diff --git a/test/fixtures/wpt/streams/piping/WEB_FEATURES.yml b/test/fixtures/wpt/streams/piping/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..8cf3517baf08a4
--- /dev/null
+++ b/test/fixtures/wpt/streams/piping/WEB_FEATURES.yml
@@ -0,0 +1,3 @@
+features:
+- name: streams
+  files: "**"
diff --git a/test/fixtures/wpt/streams/readable-byte-streams/WEB_FEATURES.yml b/test/fixtures/wpt/streams/readable-byte-streams/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..a35508fc0dc65d
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-byte-streams/WEB_FEATURES.yml
@@ -0,0 +1,3 @@
+features:
+- name: readable-byte-streams
+  files: "**"
diff --git a/test/fixtures/wpt/streams/readable-byte-streams/bad-buffers-and-views.any.js b/test/fixtures/wpt/streams/readable-byte-streams/bad-buffers-and-views.any.js
index afcc61e6800a28..eae8dde03f6b8d 100644
--- a/test/fixtures/wpt/streams/readable-byte-streams/bad-buffers-and-views.any.js
+++ b/test/fixtures/wpt/streams/readable-byte-streams/bad-buffers-and-views.any.js
@@ -123,8 +123,7 @@ promise_test(t => {
 async_test(t => {
   const stream = new ReadableStream({
     pull: t.step_func_done(c => {
-      // Detach it by reading into it
-      reader.read(c.byobRequest.view);
+      c.byobRequest.view.buffer.transfer();
 
       assert_throws_js(TypeError, () => c.byobRequest.respond(1),
         'respond() must throw if the corresponding view has become detached');
@@ -141,9 +140,7 @@ async_test(t => {
   const stream = new ReadableStream({
     pull: t.step_func_done(c => {
       c.close();
-
-      // Detach it by reading into it
-      reader.read(c.byobRequest.view);
+      c.byobRequest.view.buffer.transfer();
 
       assert_throws_js(TypeError, () => c.byobRequest.respond(0),
         'respond() must throw if the corresponding view has become detached');
@@ -159,9 +156,8 @@ async_test(t => {
 async_test(t => {
   const stream = new ReadableStream({
     pull: t.step_func_done(c => {
-      // Detach it by reading into it
       const view = new Uint8Array([1, 2, 3]);
-      reader.read(view);
+      view.buffer.transfer();
 
       assert_throws_js(TypeError, () => c.byobRequest.respondWithNewView(view));
     }),
@@ -364,8 +360,7 @@ async_test(t => {
 async_test(t => {
   const stream = new ReadableStream({
     pull: t.step_func_done(c => {
-      // Detach it by reading into it
-      reader.read(c.byobRequest.view);
+      c.byobRequest.view.buffer.transfer();
 
       assert_throws_js(TypeError, () => c.enqueue(new Uint8Array([1])),
         'enqueue() must throw if the BYOB request\'s buffer has become detached');
@@ -382,9 +377,7 @@ async_test(t => {
   const stream = new ReadableStream({
     pull: t.step_func_done(c => {
       c.close();
-
-      // Detach it by reading into it
-      reader.read(c.byobRequest.view);
+      c.byobRequest.view.buffer.transfer();
 
       assert_throws_js(TypeError, () => c.enqueue(new Uint8Array([1])),
         'enqueue() must throw if the BYOB request\'s buffer has become detached');
diff --git a/test/fixtures/wpt/streams/readable-byte-streams/crashtests/tee-locked-stream.any.js b/test/fixtures/wpt/streams/readable-byte-streams/crashtests/tee-locked-stream.any.js
new file mode 100644
index 00000000000000..285b427e277862
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-byte-streams/crashtests/tee-locked-stream.any.js
@@ -0,0 +1,9 @@
+// META: global=window,worker
+'use strict';
+
+test(() => {
+   const byteReadable = new ReadableStream({type: 'bytes'});
+   byteReadable.getReader();
+   assert_throws_js(TypeError, () => byteReadable.tee(), 'byteReadable.tee() must throw');
+}, 'tee() on a locked byte stream does not crash');
+
diff --git a/test/fixtures/wpt/streams/readable-byte-streams/general.any.js b/test/fixtures/wpt/streams/readable-byte-streams/general.any.js
index 4b0c73865f7cf9..50f4f019ff220f 100644
--- a/test/fixtures/wpt/streams/readable-byte-streams/general.any.js
+++ b/test/fixtures/wpt/streams/readable-byte-streams/general.any.js
@@ -236,6 +236,29 @@ promise_test(t => {
   });
 }, 'ReadableStream with byte source: Test that erroring a stream does not release a BYOB reader automatically');
 
+promise_test(async t => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      c.enqueue(new Uint8Array([1, 2, 3]));
+    }
+  });
+
+  const reader1 = rs.getReader({mode: 'byob'});
+  reader1.releaseLock();
+
+  const reader2 = rs.getReader({mode: 'byob'});
+
+  // Should be a no-op
+  reader1.releaseLock();
+
+  const result = await reader2.read(new Uint8Array([0, 0, 0]));
+  assert_typed_array_equals(result.value, new Uint8Array([1, 2, 3]),
+    'read() should still work on reader2 even after reader1 is released');
+  assert_false(result.done, 'done');
+
+}, 'ReadableStream with byte source: cannot use an already-released BYOB reader to unlock a stream again');
+
 promise_test(async t => {
   const stream = new ReadableStream({
     type: 'bytes'
@@ -992,6 +1015,69 @@ promise_test(() => {
 }, 'ReadableStream with byte source: respond(3) to read(view) with 2 element Uint16Array enqueues the 1 byte ' +
    'remainder');
 
+promise_test(() => {
+  let pullCount = 0;
+
+  let controller;
+  let byobRequest;
+  let viewInfo;
+
+  const stream = new ReadableStream({
+    start(c) {
+      controller = c;
+    },
+    pull() {
+      ++pullCount;
+
+      byobRequest = controller.byobRequest;
+      const view = byobRequest.view;
+      viewInfo = extractViewInfo(view);
+
+      view[0] = 0x01;
+      view[1] = 0x02;
+      view[2] = 0x03;
+
+      controller.byobRequest.respond(3);
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const read1 = reader.read(new Uint16Array(2));
+  const read2 = reader.read(new Uint8Array(1));
+
+  return read1.then(result => {
+    assert_equals(pullCount, 1);
+
+    assert_false(result.done, 'done');
+
+    const view = result.value;
+    assert_equals(view.byteOffset, 0, 'byteOffset');
+    assert_equals(view.byteLength, 2, 'byteLength');
+
+    const dataView = new DataView(view.buffer, view.byteOffset, view.byteLength);
+    assert_equals(dataView.getUint16(0), 0x0102);
+
+    return read2;
+  }).then(result => {
+    assert_equals(pullCount, 1);
+    assert_not_equals(byobRequest, null, 'byobRequest must not be null');
+    assert_equals(viewInfo.constructor, Uint8Array, 'view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 4, 'view.buffer.byteLength should be 4');
+    assert_equals(viewInfo.byteOffset, 0, 'view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 4, 'view.byteLength should be 4');
+
+    assert_false(result.done, 'done');
+
+    const view = result.value;
+    assert_equals(view.byteOffset, 0, 'byteOffset');
+    assert_equals(view.byteLength, 1, 'byteLength');
+
+    assert_equals(view[0], 0x03);
+  });
+}, 'ReadableStream with byte source: respond(3) to read(view) with 2 element Uint16Array fulfills second read(view) ' +
+   'with the 1 byte remainder');
+
 promise_test(t => {
   const stream = new ReadableStream({
     start(controller) {
diff --git a/test/fixtures/wpt/streams/readable-byte-streams/templated.any.js b/test/fixtures/wpt/streams/readable-byte-streams/templated.any.js
new file mode 100644
index 00000000000000..e4c10f7685962e
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-byte-streams/templated.any.js
@@ -0,0 +1,24 @@
+// META: global=window,worker,shadowrealm
+// META: script=../resources/test-utils.js
+// META: script=../resources/rs-test-templates.js
+'use strict';
+
+templatedRSEmpty('ReadableStream with byte source (empty)', () => {
+  return new ReadableStream({ type: 'bytes' });
+});
+
+templatedRSEmptyReader('ReadableStream with byte source (empty) default reader', () => {
+  const stream = new ReadableStream({ type: 'bytes' });
+  const reader = stream.getReader();
+  return { stream, reader, read: () => reader.read() };
+});
+
+templatedRSEmptyReader('ReadableStream with byte source (empty) BYOB reader', () => {
+  const stream = new ReadableStream({ type: 'bytes' });
+  const reader = stream.getReader({ mode: 'byob' });
+  return { stream, reader, read: () => reader.read(new Uint8Array([0])) };
+});
+
+templatedRSThrowAfterCloseOrError('ReadableStream with byte source', (extras) => {
+  return new ReadableStream({ type: 'bytes', ...extras });
+});
diff --git a/test/fixtures/wpt/streams/readable-streams/WEB_FEATURES.yml b/test/fixtures/wpt/streams/readable-streams/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..ad2cb549631fd2
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-streams/WEB_FEATURES.yml
@@ -0,0 +1,14 @@
+features:
+- name: streams
+  files:
+    - "*"
+    - "!async-iterator.any.js"
+    - "!from.any.js"
+    # 'owning' type is not yet standardized
+    - "!owning-type*"
+- name: async-iterable-streams
+  files:
+    - async-iterator.any.js
+- name: readablestream-from
+  files:
+    - from.any.js
diff --git a/test/fixtures/wpt/streams/readable-streams/crashtests/WEB_FEATURES.yml b/test/fixtures/wpt/streams/readable-streams/crashtests/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..f4eaacc3edb435
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-streams/crashtests/WEB_FEATURES.yml
@@ -0,0 +1,7 @@
+features:
+- name: streams
+  files:
+    - strategy-worker-terminate.html
+- name: readablestream-from
+  files:
+    - from-cross-realm.https.html
diff --git a/test/fixtures/wpt/streams/readable-streams/crashtests/exception-during-size-while-pulling.html b/test/fixtures/wpt/streams/readable-streams/crashtests/exception-during-size-while-pulling.html
new file mode 100644
index 00000000000000..1229b690d3910b
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-streams/crashtests/exception-during-size-while-pulling.html
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<html class="test-wait">
+<meta charset="utf-8">
+<title>ReadableStream size algorithm throws during enqueue</title>
+<script>
+  let throwOnSize = false;
+  let pullCount = 0;
+  const rs = new ReadableStream(
+    {
+      pull(controller) {
+        pullCount++;
+        if (pullCount <= 2) {
+          controller.enqueue({});
+        } else {
+          throwOnSize = true;
+          try {
+            controller.enqueue({});
+          } catch (e) {
+          }
+        }
+      },
+    },
+    {
+      size() {
+        if (throwOnSize) {
+          throw new Error("size algorithm threw");
+        }
+        return 1;
+      },
+      highWaterMark: 10,
+    }
+  );
+  new Response(rs).text().catch(() => {
+    document.documentElement.classList.remove("test-wait");
+  });
+</script>
diff --git a/test/fixtures/wpt/streams/readable-streams/crashtests/garbage-collection.any.js b/test/fixtures/wpt/streams/readable-streams/crashtests/garbage-collection.any.js
new file mode 100644
index 00000000000000..6e9d80c41425b1
--- /dev/null
+++ b/test/fixtures/wpt/streams/readable-streams/crashtests/garbage-collection.any.js
@@ -0,0 +1,38 @@
+// META: global=window,worker
+// META: script=/common/gc.js
+'use strict';
+
+// See https://crbug.com/335506658 for details.
+promise_test(async () => {
+  const closed = new ReadableStream({
+      pull(controller) {
+        controller.enqueue('is there anybody in there?');
+      }
+  }).getReader().closed;
+  // 3 GCs are actually required to trigger the bug at time of writing.
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream along with its reader should not crash');
+
+promise_test(async () => {
+  let reader = new ReadableStream({
+      pull() { }
+  }).getReader();
+  const promise = reader.read();
+  reader = null;
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream with a pending read should not crash');
+
+promise_test(async () => {
+  let reader = new ReadableStream({
+      type: "bytes",
+      pull() { return new Promise(resolve => {}); }
+  }).getReader({mode: "byob"});
+  const promise = reader.read(new Uint8Array(42));
+  reader = null;
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream with a pending BYOB read should not crash');
+
+
diff --git a/test/fixtures/wpt/streams/readable-streams/from.any.js b/test/fixtures/wpt/streams/readable-streams/from.any.js
index 2a4212ab890606..2b28a05fee398c 100644
--- a/test/fixtures/wpt/streams/readable-streams/from.any.js
+++ b/test/fixtures/wpt/streams/readable-streams/from.any.js
@@ -150,6 +150,12 @@ const badIterables = [
   ['an object with a non-callable @@asyncIterator method', {
     [Symbol.asyncIterator]: 42
   }],
+  ['an object with an @@iterator method returning a non-object', {
+    [Symbol.iterator]: () => 42
+  }],
+  ['an object with an @@asyncIterator method returning a non-object', {
+    [Symbol.asyncIterator]: () => 42
+  }],
 ];
 
 for (const [label, iterable] of badIterables) {
@@ -244,6 +250,64 @@ promise_test(async t => {
 
 }, `ReadableStream.from: stream errors when next() rejects`);
 
+promise_test(async t => {
+  const theError = new Error('a unique string');
+
+  const iterable = {
+    next() {
+      throw theError;
+    },
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await Promise.all([
+    promise_rejects_exactly(t, theError, reader.read()),
+    promise_rejects_exactly(t, theError, reader.closed)
+  ]);
+
+}, 'ReadableStream.from: stream errors when next() throws synchronously');
+
+promise_test(async t => {
+
+  const iterable = {
+    next() {
+      return 42; // not a promise or an iterator result
+    },
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await Promise.all([
+    promise_rejects_js(t, TypeError, reader.read()),
+    promise_rejects_js(t, TypeError, reader.closed)
+  ]);
+
+}, 'ReadableStream.from: stream errors when next() returns a non-object');
+
+promise_test(async t => {
+
+  const iterable = {
+    next() {
+      return Promise.resolve(42); // not an iterator result
+    },
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await Promise.all([
+    promise_rejects_js(t, TypeError, reader.read()),
+    promise_rejects_js(t, TypeError, reader.closed)
+  ]);
+
+}, 'ReadableStream.from: stream errors when next() fulfills with a non-object');
+
 promise_test(async t => {
 
   const iterable = {
@@ -360,6 +424,93 @@ promise_test(async t => {
 
 }, `ReadableStream.from: return() is not called when iterator completes normally`);
 
+promise_test(async t => {
+
+  const theError = new Error('a unique string');
+
+  const iterable = {
+    next: t.unreached_func('next() should not be called'),
+    throw: t.unreached_func('throw() should not be called'),
+    // no return method
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await Promise.all([
+    reader.cancel(theError),
+    reader.closed
+  ]);
+
+}, `ReadableStream.from: cancel() resolves when return() method is missing`);
+
+promise_test(async t => {
+
+  const theError = new Error('a unique string');
+
+  const iterable = {
+    next: t.unreached_func('next() should not be called'),
+    throw: t.unreached_func('throw() should not be called'),
+    return: 42,
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await promise_rejects_js(t, TypeError, reader.cancel(theError), 'cancel() should reject with a TypeError');
+
+  await reader.closed;
+
+}, `ReadableStream.from: cancel() rejects when return() is not a method`);
+
+promise_test(async t => {
+
+  const cancelReason = new Error('cancel reason');
+  const rejectError = new Error('reject error');
+
+  const iterable = {
+    next: t.unreached_func('next() should not be called'),
+    throw: t.unreached_func('throw() should not be called'),
+    async return() {
+      throw rejectError;
+    },
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await promise_rejects_exactly(t, rejectError, reader.cancel(cancelReason), 'cancel() should reject with error from return()');
+
+  await reader.closed;
+
+}, `ReadableStream.from: cancel() rejects when return() rejects`);
+
+promise_test(async t => {
+
+  const cancelReason = new Error('cancel reason');
+  const rejectError = new Error('reject error');
+
+  const iterable = {
+    next: t.unreached_func('next() should not be called'),
+    throw: t.unreached_func('throw() should not be called'),
+    return() {
+      throw rejectError;
+    },
+    [Symbol.asyncIterator]: () => iterable
+  };
+
+  const rs = ReadableStream.from(iterable);
+  const reader = rs.getReader();
+
+  await promise_rejects_exactly(t, rejectError, reader.cancel(cancelReason), 'cancel() should reject with error from return()');
+
+  await reader.closed;
+
+}, `ReadableStream.from: cancel() rejects when return() throws synchronously`);
+
 promise_test(async t => {
 
   const theError = new Error('a unique string');
diff --git a/test/fixtures/wpt/streams/readable-streams/garbage-collection.any.js b/test/fixtures/wpt/streams/readable-streams/garbage-collection.any.js
index 13bd1fb3437877..abcb4cf21b8955 100644
--- a/test/fixtures/wpt/streams/readable-streams/garbage-collection.any.js
+++ b/test/fixtures/wpt/streams/readable-streams/garbage-collection.any.js
@@ -69,3 +69,22 @@ promise_test(async () => {
     'old reader should still be locking the stream even after garbage collection'));
 
 }, 'Garbage-collecting a ReadableStreamDefaultReader should not unlock its stream');
+
+promise_test(async () => {
+
+  const promise = (() => {
+    const rs = new ReadableStream({
+      pull(controller) {
+        controller.enqueue('words');
+      }
+    });
+    const reader = rs.getReader();
+    return reader.read();
+  })();
+  await garbageCollect();
+  const {value, done} = await promise;
+  // If we get here, the test passed.
+  assert_equals(value, 'words', 'value should be words');
+  assert_false(done, 'we should not be done');
+
+}, 'A ReadableStream and its reader should not be garbage collected while there is a read promise pending');
diff --git a/test/fixtures/wpt/streams/readable-streams/templated.any.js b/test/fixtures/wpt/streams/readable-streams/templated.any.js
index dc75b805a10d63..4f2440c0880bb7 100644
--- a/test/fixtures/wpt/streams/readable-streams/templated.any.js
+++ b/test/fixtures/wpt/streams/readable-streams/templated.any.js
@@ -13,7 +13,9 @@ templatedRSEmpty('ReadableStream (empty)', () => {
 });
 
 templatedRSEmptyReader('ReadableStream (empty) reader', () => {
-  return streamAndDefaultReader(new ReadableStream());
+  const stream = new ReadableStream();
+  const reader = stream.getReader();
+  return { stream, reader, read: () => reader.read() };
 });
 
 templatedRSClosed('ReadableStream (closed via call in start)', () => {
@@ -138,6 +140,10 @@ templatedRSTwoChunksClosedReader('ReadableStream (two chunks enqueued, then clos
   return result;
 }, chunks);
 
+templatedRSThrowAfterCloseOrError('ReadableStream', (extras) => {
+  return new ReadableStream({ ...extras });
+});
+
 function streamAndDefaultReader(stream) {
   return { stream, reader: stream.getReader() };
 }
diff --git a/test/fixtures/wpt/streams/resources/rs-test-templates.js b/test/fixtures/wpt/streams/resources/rs-test-templates.js
index 25751c477f5dc8..73ef0463768d23 100644
--- a/test/fixtures/wpt/streams/resources/rs-test-templates.js
+++ b/test/fixtures/wpt/streams/resources/rs-test-templates.js
@@ -200,7 +200,7 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   test(() => {
 
-    const stream = factory().stream;
+    const { stream } = factory();
 
     assert_true(stream.locked, 'locked getter should return true');
 
@@ -208,9 +208,9 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   promise_test(t => {
 
-    const reader = factory().reader;
+    const { read } = factory();
 
-    reader.read().then(
+    read().then(
       t.unreached_func('read() should not fulfill'),
       t.unreached_func('read() should not reject')
     );
@@ -221,14 +221,14 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   promise_test(t => {
 
-    const reader = factory().reader;
+    const { read } = factory();
 
-    reader.read().then(
+    read().then(
       t.unreached_func('read() should not fulfill'),
       t.unreached_func('read() should not reject')
     );
 
-    reader.read().then(
+    read().then(
       t.unreached_func('read() should not fulfill'),
       t.unreached_func('read() should not reject')
     );
@@ -239,26 +239,24 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   test(() => {
 
-    const reader = factory().reader;
-    assert_not_equals(reader.read(), reader.read(), 'the promises returned should be distinct');
+    const { read } = factory();
+    assert_not_equals(read(), read(), 'the promises returned should be distinct');
 
   }, label + ': read() should return distinct promises each time');
 
   test(() => {
 
-    const stream = factory().stream;
+    const { stream } = factory();
     assert_throws_js(TypeError, () => stream.getReader(), 'stream.getReader() should throw a TypeError');
 
   }, label + ': getReader() again on the stream should fail');
 
   promise_test(async t => {
 
-    const streamAndReader = factory();
-    const stream = streamAndReader.stream;
-    const reader = streamAndReader.reader;
+    const { stream, reader, read } = factory();
 
-    const read1 = reader.read();
-    const read2 = reader.read();
+    const read1 = read();
+    const read2 = read();
     const closed = reader.closed;
 
     reader.releaseLock();
@@ -275,19 +273,19 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   promise_test(t => {
 
-    const reader = factory().reader;
+    const { reader, read } = factory();
     reader.releaseLock();
 
     return Promise.all([
-      promise_rejects_js(t, TypeError, reader.read()),
-      promise_rejects_js(t, TypeError, reader.read())
+      promise_rejects_js(t, TypeError, read()),
+      promise_rejects_js(t, TypeError, read())
     ]);
 
   }, label + ': releasing the lock should cause further read() calls to reject with a TypeError');
 
   promise_test(t => {
 
-    const reader = factory().reader;
+    const { reader } = factory();
 
     const closedBefore = reader.closed;
     reader.releaseLock();
@@ -301,9 +299,7 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   test(() => {
 
-    const streamAndReader = factory();
-    const stream = streamAndReader.stream;
-    const reader = streamAndReader.reader;
+    const { stream, reader } = factory();
 
     reader.releaseLock();
     assert_false(stream.locked, 'locked getter should return false');
@@ -312,10 +308,10 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   promise_test(() => {
 
-    const reader = factory().reader;
+    const { reader, read } = factory();
     reader.cancel();
 
-    return reader.read().then(r => {
+    return read().then(r => {
       assert_object_equals(r, { value: undefined, done: true }, 'read()ing from the reader should give a done result');
     });
 
@@ -323,7 +319,7 @@ self.templatedRSEmptyReader = (label, factory) => {
 
   promise_test(t => {
 
-    const stream = factory().stream;
+    const { stream } = factory();
     return promise_rejects_js(t, TypeError, stream.cancel());
 
   }, label + ': canceling via the stream should fail');
@@ -719,3 +715,62 @@ self.templatedRSTeeCancel = (label, factory) => {
   }, `${label}: erroring a teed stream should properly handle canceled branches`);
 
 };
+
+self.templatedRSThrowAfterCloseOrError = (label, factory) => {
+  test(() => {}, 'Running templatedRSThrowAfterCloseOrError with ' + label);
+
+  const theError = new Error('a unique string');
+
+  promise_test(async t => {
+    let controller;
+    const stream = factory({
+      start: t.step_func((c) => {
+        controller = c;
+      })
+    });
+
+    controller.close();
+
+    assert_throws_js(TypeError, () => controller.enqueue(new Uint8Array([1])));
+  }, `${label}: enqueue() throws after close()`);
+
+  promise_test(async t => {
+    let controller;
+    const stream = factory({
+      start: t.step_func((c) => {
+        controller = c;
+      })
+    });
+
+    controller.enqueue(new Uint8Array([1]));
+    controller.close();
+
+    assert_throws_js(TypeError, () => controller.enqueue(new Uint8Array([2])));
+  }, `${label}: enqueue() throws after enqueue() and close()`);
+
+  promise_test(async t => {
+    let controller;
+    const stream = factory({
+      start: t.step_func((c) => {
+        controller = c;
+      })
+    });
+
+    controller.error(theError);
+
+    assert_throws_js(TypeError, () => controller.enqueue(new Uint8Array([1])));
+  }, `${label}: enqueue() throws after error()`);
+
+  promise_test(async t => {
+    let controller;
+    const stream = factory({
+      start: t.step_func((c) => {
+        controller = c;
+      })
+    });
+
+    controller.error(theError);
+
+    assert_throws_js(TypeError, () => controller.close());
+  }, `${label}: close() throws after error()`);
+};
diff --git a/test/fixtures/wpt/streams/transferable/WEB_FEATURES.yml b/test/fixtures/wpt/streams/transferable/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..4ecacf5edbc7da
--- /dev/null
+++ b/test/fixtures/wpt/streams/transferable/WEB_FEATURES.yml
@@ -0,0 +1,3 @@
+features:
+- name: transferable-streams
+  files: "**"
diff --git a/test/fixtures/wpt/streams/transform-streams/WEB_FEATURES.yml b/test/fixtures/wpt/streams/transform-streams/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..f39dc16de4c731
--- /dev/null
+++ b/test/fixtures/wpt/streams/transform-streams/WEB_FEATURES.yml
@@ -0,0 +1,8 @@
+features:
+- name: streams
+  files:
+    - "*"
+    - "!cancel.any.js"
+- name: transformstream-transformer-cancel
+  files:
+    - cancel.any.js
diff --git a/test/fixtures/wpt/streams/transform-streams/cancel.any.js b/test/fixtures/wpt/streams/transform-streams/cancel.any.js
index 5c7fc4eae5d55b..9b369bfb7c68b4 100644
--- a/test/fixtures/wpt/streams/transform-streams/cancel.any.js
+++ b/test/fixtures/wpt/streams/transform-streams/cancel.any.js
@@ -113,3 +113,93 @@ promise_test(async t => {
   const closePromise = ts.readable.cancel(1);
   await promise_rejects_exactly(t, thrownError, closePromise, 'closePromise should reject with thrownError');
 }, 'writable.abort() and readable.cancel() should reject if a transformer.cancel() calls controller.error()');
+
+promise_test(async t => {
+  const cancelReason = new Error('cancel reason');
+  let controller;
+  let cancelPromise;
+  let flushCalled = false;
+  const ts = new TransformStream({
+    start(c) {
+      controller = c;
+    },
+    flush() {
+      flushCalled = true;
+      cancelPromise = ts.readable.cancel(cancelReason);
+    },
+    cancel: t.unreached_func('cancel should not be called')
+  });
+  await flushAsyncEvents(); // ensure stream is started
+  await ts.writable.close();
+  assert_true(flushCalled, 'flush() was called');
+  await cancelPromise;
+}, 'readable.cancel() should not call cancel() when flush() is already called from writable.close()');
+
+promise_test(async t => {
+  const cancelReason = new Error('cancel reason');
+  const abortReason = new Error('abort reason');
+  let cancelCalls = 0;
+  let controller;
+  let cancelPromise;
+  const ts = new TransformStream({
+    start(c) {
+      controller = c;
+    },
+    cancel() {
+      if (++cancelCalls === 1) {
+        cancelPromise = ts.readable.cancel(cancelReason);
+      }
+    },
+    flush: t.unreached_func('flush should not be called')
+  });
+  await flushAsyncEvents(); // ensure stream is started
+  await ts.writable.abort(abortReason);
+  assert_equals(cancelCalls, 1);
+  await cancelPromise;
+  assert_equals(cancelCalls, 1);
+}, 'readable.cancel() should not call cancel() again when already called from writable.abort()');
+
+promise_test(async t => {
+  const cancelReason = new Error('cancel reason');
+  let controller;
+  let closePromise;
+  let cancelCalled = false;
+  const ts = new TransformStream({
+    start(c) {
+      controller = c;
+    },
+    cancel() {
+      cancelCalled = true;
+      closePromise = ts.writable.close();
+    },
+    flush: t.unreached_func('flush should not be called')
+  });
+  await flushAsyncEvents(); // ensure stream is started
+  await ts.readable.cancel(cancelReason);
+  assert_true(cancelCalled, 'cancel() was called');
+  await closePromise;
+}, 'writable.close() should not call flush() when cancel() is already called from readable.cancel()');
+
+promise_test(async t => {
+  const cancelReason = new Error('cancel reason');
+  const abortReason = new Error('abort reason');
+  let cancelCalls = 0;
+  let controller;
+  let abortPromise;
+  const ts = new TransformStream({
+    start(c) {
+      controller = c;
+    },
+    cancel() {
+      if (++cancelCalls === 1) {
+        abortPromise = ts.writable.abort(abortReason);
+      }
+    },
+    flush: t.unreached_func('flush should not be called')
+  });
+  await flushAsyncEvents(); // ensure stream is started
+  await promise_rejects_exactly(t, abortReason, ts.readable.cancel(cancelReason));
+  assert_equals(cancelCalls, 1);
+  await promise_rejects_exactly(t, abortReason, abortPromise);
+  assert_equals(cancelCalls, 1);
+}, 'writable.abort() should not call cancel() again when already called from readable.cancel()');
diff --git a/test/fixtures/wpt/streams/writable-streams/WEB_FEATURES.yml b/test/fixtures/wpt/streams/writable-streams/WEB_FEATURES.yml
new file mode 100644
index 00000000000000..8cf3517baf08a4
--- /dev/null
+++ b/test/fixtures/wpt/streams/writable-streams/WEB_FEATURES.yml
@@ -0,0 +1,3 @@
+features:
+- name: streams
+  files: "**"
diff --git a/test/fixtures/wpt/streams/writable-streams/aborting.any.js b/test/fixtures/wpt/streams/writable-streams/aborting.any.js
index 9171dbe158f00c..9d8e80b1de63c5 100644
--- a/test/fixtures/wpt/streams/writable-streams/aborting.any.js
+++ b/test/fixtures/wpt/streams/writable-streams/aborting.any.js
@@ -1472,16 +1472,96 @@ promise_test(async t => {
 
 promise_test(async t => {
   let ctrl;
+  let abortPromise;
+  let abortPromiseFromSignal;
+  const e1 = SyntaxError();
+  const e2 = TypeError();
+  const ws = new WritableStream({
+    start(c) { ctrl = c; },
+  });
+
+  const writer = ws.getWriter();
+  ctrl.signal.addEventListener('abort', () => {
+    abortPromiseFromSignal = writer.abort(e2);
+  });
+  abortPromise = writer.abort(e1);
+  assert_true(ctrl.signal.aborted);
+
+  await Promise.all([
+    abortPromise,
+    abortPromiseFromSignal,
+    promise_rejects_exactly(t, e2, writer.closed, 'closed')
+  ]);
+}, 'recursive abort() call from abort() aborting signal (not started)');
+
+promise_test(async t => {
+  let ctrl;
+  let abortPromise;
+  let abortPromiseFromSignal;
   const e1 = SyntaxError();
   const e2 = TypeError();
   const ws = new WritableStream({
     start(c) { ctrl = c; },
   });
+  await flushAsyncEvents(); // ensure stream is started
+
+  const writer = ws.getWriter();
+  ctrl.signal.addEventListener('abort', () => {
+    abortPromiseFromSignal = writer.abort(e2);
+  });
+  abortPromise = writer.abort(e1);
+  assert_true(ctrl.signal.aborted);
+
+  await Promise.all([
+    abortPromise,
+    abortPromiseFromSignal,
+    promise_rejects_exactly(t, e2, writer.closed, 'closed')
+  ]);
+}, 'recursive abort() call from abort() aborting signal');
+
+promise_test(async t => {
+  let ctrl;
+  let abortPromise;
+  let closePromiseFromSignal;
+  const theError = SyntaxError();
+  const ws = new WritableStream({
+    start(c) { ctrl = c; },
+  });
+
+  const writer = ws.getWriter();
+  ctrl.signal.addEventListener('abort', () => {
+    closePromiseFromSignal = writer.close();
+  });
+  abortPromise = writer.abort(theError);
+  assert_true(ctrl.signal.aborted);
+
+  await Promise.all([
+    abortPromise,
+    promise_rejects_exactly(t, theError, closePromiseFromSignal, 'closed'),
+    promise_rejects_exactly(t, theError, writer.closed, 'closed')
+  ]);
+}, 'recursive close() call from abort() aborting signal (not started)');
+
+promise_test(async t => {
+  let ctrl;
+  let abortPromise;
+  let closePromiseFromSignal;
+  const theError = SyntaxError();
+  const ws = new WritableStream({
+    start(c) { ctrl = c; },
+  });
+  await flushAsyncEvents(); // ensure stream is started
 
   const writer = ws.getWriter();
-  ctrl.signal.addEventListener('abort', () => writer.abort(e2));
-  writer.abort(e1);
+  ctrl.signal.addEventListener('abort', () => {
+    closePromiseFromSignal = writer.close();
+  });
+  abortPromise = writer.abort(theError);
   assert_true(ctrl.signal.aborted);
 
-  await promise_rejects_exactly(t, e2, writer.closed, 'closed');
-}, 'recursive abort() call');
+  await Promise.all([
+    abortPromise,
+    closePromiseFromSignal,
+    writer.closed
+  ]);
+}, 'recursive close() call from abort() aborting signal');
diff --git a/test/fixtures/wpt/streams/writable-streams/close.any.js b/test/fixtures/wpt/streams/writable-streams/close.any.js
index 45261e7ca7e01d..3b2c07cc3bfea1 100644
--- a/test/fixtures/wpt/streams/writable-streams/close.any.js
+++ b/test/fixtures/wpt/streams/writable-streams/close.any.js
@@ -468,3 +468,14 @@ promise_test(t => {
 
   return promise_rejects_js(t, TypeError, ws.close(), 'close should reject');
 }, 'close() on a stream with a pending close should reject');
+
+// See https://github.com/whatwg/streams/issues/1341.
+promise_test(async t => {
+  const ws = new WritableStream();
+  const writer = ws.getWriter();
+
+  await writer.write(1);
+  await writer.close();
+
+  return promise_rejects_js(t, TypeError, writer.write(2), 'write should reject');
+}, 'write() on a closed stream should reject');
diff --git a/test/fixtures/wpt/streams/writable-streams/constructor.any.js b/test/fixtures/wpt/streams/writable-streams/constructor.any.js
index 0abc7ef545ea0b..bb382a33b8e0c4 100644
--- a/test/fixtures/wpt/streams/writable-streams/constructor.any.js
+++ b/test/fixtures/wpt/streams/writable-streams/constructor.any.js
@@ -87,6 +87,10 @@ test(() => {
   new WritableStream();
 }, 'WritableStream should be constructible with no arguments');
 
+test(() => {
+  assert_throws_js(RangeError, () => new WritableStream({ type: 'bytes' }), 'constructor should throw');
+}, `WritableStream can't be constructed with a defined type`);
+
 test(() => {
   const underlyingSink = { get start() { throw error1; } };
   const queuingStrategy = { highWaterMark: 0, get size() { throw error2; } };
diff --git a/test/fixtures/wpt/streams/writable-streams/crashtests/garbage-collection.any.js b/test/fixtures/wpt/streams/writable-streams/crashtests/garbage-collection.any.js
new file mode 100644
index 00000000000000..9f64e9b7a8ac7b
--- /dev/null
+++ b/test/fixtures/wpt/streams/writable-streams/crashtests/garbage-collection.any.js
@@ -0,0 +1,90 @@
+// META: global=window,worker
+// META: script=/common/gc.js
+'use strict';
+
+// See https://crbug.com/390646657 for details.
+promise_test(async () => {
+  const written = new WritableStream({
+    write(chunk) {
+      return new Promise(resolve => {});
+    }
+  }).getWriter().write('just nod if you can hear me');
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream writer with a pending write should not crash');
+
+promise_test(async () => {
+  const closed = new WritableStream({
+    write(chunk) { }
+  }).getWriter().closed;
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream writer should not crash with closed promise is retained');
+
+promise_test(async () => {
+  let writer = new WritableStream({
+    write(chunk) { return new Promise(resolve => {}); },
+    close() { return new Promise(resolve => {}); }
+  }).getWriter();
+  writer.write('is there anyone home?');
+  writer.close();
+  writer = null;
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream writer should not crash with close promise pending');
+
+promise_test(async () => {
+  const ready = new WritableStream({
+    write(chunk) { }
+  }, {highWaterMark: 0}).getWriter().ready;
+  for (let i = 0; i < 5; ++i)
+    await garbageCollect();
+}, 'Garbage-collecting a stream writer should not crash when backpressure is being applied');
+
+// Repro for https://crbug.com/455800266
+promise_test(async () => {
+  // This logic is wrapped in a function to make it easy to garbage collect all
+  // references to the WritableStream.
+  const createWritableStream = async () => {
+    const WRITE_COUNT = 2;
+    let writes_done = 0;
+    const { promise, resolve } = Promise.withResolvers();
+
+    const ws = new WritableStream({
+      write() {
+        if (writes_done === WRITE_COUNT) {
+          // Will never resolve, leaving the write operation pending.
+          return new Promise(resolve => { });
+        }
+        ++writes_done;
+        return promise;
+      }
+    });
+
+    const writer = ws.getWriter();
+    await writer.ready;
+
+    const writeChunks = () => {
+      for (let i = 0; i < WRITE_COUNT; ++i) {
+        const ready = writer.ready;
+        writer.write("chunk");
+      }
+    };
+
+    // Apply backpressure.
+    writeChunks();
+
+    // Release backpressure.
+    resolve();
+    await writer.ready;
+
+    // Apply backpressure again.
+    writeChunks();
+  };
+
+  await createWritableStream();
+
+  for (let i = 0; i < 5; ++i) {
+    await garbageCollect();
+  }
+}, "WritableStream should not crash when garbage collected with backpressure");
diff --git a/test/fixtures/wpt/streams/writable-streams/garbage-collection.any.js b/test/fixtures/wpt/streams/writable-streams/garbage-collection.any.js
new file mode 100644
index 00000000000000..5e39e7c60d2c33
--- /dev/null
+++ b/test/fixtures/wpt/streams/writable-streams/garbage-collection.any.js
@@ -0,0 +1,21 @@
+// META: global=window,worker,shadowrealm
+// META: script=/common/gc.js
+'use strict';
+
+promise_test(async () => {
+
+  let written = false;
+  const promise = (() => {
+    const rs = new WritableStream({
+      write() {
+        written = true;
+      }
+    });
+    const writer = rs.getWriter();
+    return writer.write('something');
+  })();
+  await garbageCollect();
+  await promise;
+  assert_true(written);
+
+}, 'A WritableStream and its writer should not be garbage collected while there is a write promise pending');
diff --git a/test/fixtures/wpt/versions.json b/test/fixtures/wpt/versions.json
index d627791ed27e0c..68dde063450d82 100644
--- a/test/fixtures/wpt/versions.json
+++ b/test/fixtures/wpt/versions.json
@@ -68,7 +68,7 @@
     "path": "resources"
   },
   "streams": {
-    "commit": "bc9dcbbf1a4c2c741ef47f47d6ede6458f40c4a4",
+    "commit": "f8f26a372f357370846226ff64db1f9cc98a1edb",
     "path": "streams"
   },
   "url": {
diff --git a/test/wpt/status/streams.json b/test/wpt/status/streams.json
index 968b3359765189..ffa7e9d65f2338 100644
--- a/test/wpt/status/streams.json
+++ b/test/wpt/status/streams.json
@@ -8,6 +8,15 @@
   "readable-streams/cross-realm-crash.window.js": {
     "skip": "Browser-specific test"
   },
+  "readable-streams/from.any.js": {
+    "fail": {
+      "note": "does not synchronously validate that the value returned by @@iterator/@@asyncIterator is an object",
+      "expected": [
+        "ReadableStream.from throws on invalid iterables; specifically an object with an @@iterator method returning a non-object",
+        "ReadableStream.from throws on invalid iterables; specifically an object with an @@asyncIterator method returning a non-object"
+      ]
+    }
+  },
   "readable-streams/owning-type-message-port.any.js": {
     "fail": {
       "note": "Readable streams with type owning are not yet supported",
@@ -43,5 +52,13 @@
   },
   "transform-streams/invalid-realm.tentative.window.js": {
     "skip": "Browser-specific test"
+  },
+  "writable-streams/aborting.any.js": {
+    "fail": {
+      "note": "Recursive abort() call from within an abort algorithm triggers ERR_INTERNAL_ASSERTION",
+      "expected": [
+        "recursive abort() call from abort() aborting signal"
+      ]
+    }
   }
 }