Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1521 insertions, 0 deletions

diff --git a/dom/streams/ReadableStream.cpp b/dom/streams/ReadableStream.cpp
new file mode 100644
index 0000000000..cc2266cbfb
--- /dev/null
+++ b/dom/streams/ReadableStream.cpp
@@ -0,0 +1,1521 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/ReadableStream.h"
+
+#include "ReadIntoRequest.h"
+#include "ReadableStreamPipeTo.h"
+#include "ReadableStreamTee.h"
+#include "StreamUtils.h"
+#include "TeeState.h"
+#include "js/Array.h"
+#include "js/Exception.h"
+#include "js/PropertyAndElement.h"
+#include "js/TypeDecls.h"
+#include "js/Value.h"
+#include "js/Iterator.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/dom/BindingCallContext.h"
+#include "mozilla/dom/ByteStreamHelpers.h"
+#include "mozilla/dom/QueueWithSizes.h"
+#include "mozilla/dom/QueuingStrategyBinding.h"
+#include "mozilla/dom/ReadRequest.h"
+#include "mozilla/dom/ReadableByteStreamController.h"
+#include "mozilla/dom/ReadableStreamBYOBReader.h"
+#include "mozilla/dom/ReadableStreamBYOBRequest.h"
+#include "mozilla/dom/ReadableStreamBinding.h"
+#include "mozilla/dom/ReadableStreamController.h"
+#include "mozilla/dom/ReadableStreamDefaultController.h"
+#include "mozilla/dom/ReadableStreamDefaultReader.h"
+#include "mozilla/dom/RootedDictionary.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/UnderlyingSourceBinding.h"
+#include "mozilla/dom/UnderlyingSourceCallbackHelpers.h"
+#include "mozilla/dom/WritableStream.h"
+#include "mozilla/dom/WritableStreamDefaultWriter.h"
+#include "nsCOMPtr.h"
+
+#include "mozilla/dom/Promise-inl.h"
+#include "nsIGlobalObject.h"
+#include "nsISupports.h"
+
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    mozilla::Variant<mozilla::Nothing,
+                     RefPtr<mozilla::dom::ReadableStreamDefaultReader>>&
+        aReader,
+    const char* aName, uint32_t aFlags = 0) {
+  if (aReader.is<RefPtr<mozilla::dom::ReadableStreamDefaultReader>>()) {
+    ImplCycleCollectionTraverse(
+        aCallback,
+        aReader.as<RefPtr<mozilla::dom::ReadableStreamDefaultReader>>(), aName,
+        aFlags);
+  }
+}
+
+inline void ImplCycleCollectionUnlink(
+    mozilla::Variant<mozilla::Nothing,
+                     RefPtr<mozilla::dom::ReadableStreamDefaultReader>>&
+        aReader) {
+  aReader = AsVariant(mozilla::Nothing());
+}
+
+namespace mozilla::dom {
+
+using namespace streams_abstract;
+
+// Only needed for refcounted objects.
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_WITH_JS_MEMBERS(
+    ReadableStream, (mGlobal, mController, mReader), (mStoredError))
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ReadableStream)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ReadableStream)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ReadableStream)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+ReadableStream::ReadableStream(nsIGlobalObject* aGlobal,
+                               HoldDropJSObjectsCaller aHoldDropCaller)
+    : mGlobal(aGlobal), mReader(nullptr), mHoldDropCaller(aHoldDropCaller) {
+  if (mHoldDropCaller == HoldDropJSObjectsCaller::Implicit) {
+    mozilla::HoldJSObjects(this);
+  }
+}
+
+ReadableStream::ReadableStream(const GlobalObject& aGlobal,
+                               HoldDropJSObjectsCaller aHoldDropCaller)
+    : mGlobal(do_QueryInterface(aGlobal.GetAsSupports())),
+      mReader(nullptr),
+      mHoldDropCaller(aHoldDropCaller) {
+  if (mHoldDropCaller == HoldDropJSObjectsCaller::Implicit) {
+    mozilla::HoldJSObjects(this);
+  }
+}
+
+ReadableStream::~ReadableStream() {
+  if (mHoldDropCaller == HoldDropJSObjectsCaller::Implicit) {
+    mozilla::DropJSObjects(this);
+  }
+}
+
+JSObject* ReadableStream::WrapObject(JSContext* aCx,
+                                     JS::Handle<JSObject*> aGivenProto) {
+  return ReadableStream_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+ReadableStreamDefaultReader* ReadableStream::GetDefaultReader() {
+  return mReader->AsDefault();
+}
+
+void ReadableStream::SetReader(ReadableStreamGenericReader* aReader) {
+  mReader = aReader;
+}
+
+namespace streams_abstract {
+
+// https://streams.spec.whatwg.org/#readable-stream-has-byob-reader
+bool ReadableStreamHasBYOBReader(ReadableStream* aStream) {
+  // Step 1. Let reader be stream.[[reader]].
+  ReadableStreamGenericReader* reader = aStream->GetReader();
+
+  // Step 2. If reader is undefined, return false.
+  if (!reader) {
+    return false;
+  }
+
+  // Step 3. If reader implements ReadableStreamBYOBReader, return true.
+  // Step 4. Return false.
+  return reader->IsBYOB();
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-has-default-reader
+bool ReadableStreamHasDefaultReader(ReadableStream* aStream) {
+  // Step 1. Let reader be stream.[[reader]].
+  ReadableStreamGenericReader* reader = aStream->GetReader();
+
+  // Step 2. If reader is undefined, return false.
+  if (!reader) {
+    return false;
+  }
+
+  // Step 3. If reader implements ReadableStreamDefaultReader, return true.
+  // Step 4. Return false.
+  return reader->IsDefault();
+}
+
+}  // namespace streams_abstract
+
+// Streams Spec: 4.2.4: https://streams.spec.whatwg.org/#rs-prototype
+/* static */
+already_AddRefed<ReadableStream> ReadableStream::Constructor(
+    const GlobalObject& aGlobal,
+    const Optional<JS::Handle<JSObject*>>& aUnderlyingSource,
+    const QueuingStrategy& aStrategy, ErrorResult& aRv) {
+  // Step 1.
+  JS::Rooted<JSObject*> underlyingSourceObj(
+      aGlobal.Context(),
+      aUnderlyingSource.WasPassed() ? aUnderlyingSource.Value() : nullptr);
+
+  // Step 2.
+  RootedDictionary<UnderlyingSource> underlyingSourceDict(aGlobal.Context());
+  if (underlyingSourceObj) {
+    JS::Rooted<JS::Value> objValue(aGlobal.Context(),
+                                   JS::ObjectValue(*underlyingSourceObj));
+    dom::BindingCallContext callCx(aGlobal.Context(),
+                                   "ReadableStream.constructor");
+    aRv.MightThrowJSException();
+    if (!underlyingSourceDict.Init(callCx, objValue)) {
+      aRv.StealExceptionFromJSContext(aGlobal.Context());
+      return nullptr;
+    }
+  }
+
+  // Step 3.
+  RefPtr<ReadableStream> readableStream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
+
+  // Step 4.
+  if (underlyingSourceDict.mType.WasPassed()) {
+    // Implicit assertion on above check.
+    MOZ_ASSERT(underlyingSourceDict.mType.Value() == ReadableStreamType::Bytes);
+
+    // Step 4.1
+    if (aStrategy.mSize.WasPassed()) {
+      aRv.ThrowRangeError("Implementation preserved member 'size'");
+      return nullptr;
+    }
+
+    // Step 4.2
+    double highWaterMark = ExtractHighWaterMark(aStrategy, 0, aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+
+    // Step 4.3
+    SetUpReadableByteStreamControllerFromUnderlyingSource(
+        aGlobal.Context(), readableStream, underlyingSourceObj,
+        underlyingSourceDict, highWaterMark, aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+
+    return readableStream.forget();
+  }
+
+  // Step 5.1 (implicit in above check)
+  // Step 5.2. Extract callback.
+  //
+  // Implementation Note: The specification demands that if the size doesn't
+  // exist, we instead would provide an algorithm that returns 1. Instead, we
+  // will teach callers that a missing callback should simply return 1, rather
+  // than gin up a fake callback here.
+  //
+  // This decision may need to be revisited if the default action ever diverges
+  // within the specification.
+  RefPtr<QueuingStrategySize> sizeAlgorithm =
+      aStrategy.mSize.WasPassed() ? &aStrategy.mSize.Value() : nullptr;
+
+  // Step 5.3
+  double highWaterMark = ExtractHighWaterMark(aStrategy, 1, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 5.4.
+  SetupReadableStreamDefaultControllerFromUnderlyingSource(
+      aGlobal.Context(), readableStream, underlyingSourceObj,
+      underlyingSourceDict, highWaterMark, sizeAlgorithm, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  return readableStream.forget();
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-from-iterable
+class ReadableStreamFromAlgorithms final
+    : public UnderlyingSourceAlgorithmsWrapper {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(
+      ReadableStreamFromAlgorithms, UnderlyingSourceAlgorithmsWrapper)
+
+  ReadableStreamFromAlgorithms(nsIGlobalObject* aGlobal,
+                               JS::Handle<JSObject*> aIteratorRecord)
+      : mGlobal(aGlobal), mIteratorRecordMaybeCrossRealm(aIteratorRecord) {
+    mozilla::HoldJSObjects(this);
+  };
+
+  // Step 3. Let startAlgorithm be an algorithm that returns undefined.
+  // Note: Provided by UnderlyingSourceAlgorithmsWrapper::StartCallback.
+
+  // Step 4. Let pullAlgorithm be the following steps:
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> PullCallbackImpl(
+      JSContext* aCx, ReadableStreamController& aController,
+      ErrorResult& aRv) override {
+    aRv.MightThrowJSException();
+
+    JS::Rooted<JSObject*> iteratorRecord(aCx, mIteratorRecordMaybeCrossRealm);
+    JSAutoRealm ar(aCx, iteratorRecord);
+
+    // Step 1. Let nextResult be IteratorNext(iteratorRecord).
+    JS::Rooted<JS::Value> nextResult(aCx);
+    if (!JS::IteratorNext(aCx, iteratorRecord, &nextResult)) {
+      // Step 2. If nextResult is an abrupt completion, return a promise
+      // rejected with nextResult.[[Value]].
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    // Step 3. Let nextPromise be a promise resolved with nextResult.[[Value]].
+    RefPtr<Promise> nextPromise = Promise::CreateInfallible(mGlobal);
+    nextPromise->MaybeResolve(nextResult);
+
+    // Step 4. Return the result of reacting to nextPromise with the following
+    // fulfillment steps, given iterResult:
+    auto result = nextPromise->ThenWithCycleCollectedArgs(
+        [](JSContext* aCx, JS::Handle<JS::Value> aIterResult, ErrorResult& aRv,
+           const RefPtr<ReadableStreamDefaultController>& aController)
+            MOZ_CAN_RUN_SCRIPT_FOR_DEFINITION -> already_AddRefed<Promise> {
+              aRv.MightThrowJSException();
+
+              // Step 4.1. If Type(iterResult) is not Object, throw a TypeError.
+              if (!aIterResult.isObject()) {
+                aRv.ThrowTypeError("next() returned a non-object value");
+                return nullptr;
+              }
+
+              JS::Rooted<JSObject*> iterResult(aCx, &aIterResult.toObject());
+
+              // Step 4.2. Let done be ? IteratorComplete(iterResult).
+              bool done = false;
+              if (!JS::IteratorComplete(aCx, iterResult, &done)) {
+                aRv.StealExceptionFromJSContext(aCx);
+                return nullptr;
+              }
+
+              // Step 4.3. If done is true:
+              if (done) {
+                // Step 4.3.1. Perform !
+                // ReadableStreamDefaultControllerClose(stream.[[controller]]).
+                ReadableStreamDefaultControllerClose(aCx, aController, aRv);
+              } else {
+                // Step 4.4. Otherwise:
+                // Step 4.4.1. Let value be ? IteratorValue(iterResult).
+                JS::Rooted<JS::Value> value(aCx);
+                if (!JS::IteratorValue(aCx, iterResult, &value)) {
+                  aRv.StealExceptionFromJSContext(aCx);
+                  return nullptr;
+                }
+
+                // Step 4.4.2. Perform !
+                // ReadableStreamDefaultControllerEnqueue(stream.[[controller]],
+                // value).
+                ReadableStreamDefaultControllerEnqueue(aCx, aController, value,
+                                                       aRv);
+              }
+
+              return nullptr;
+            },
+        RefPtr(aController.AsDefault()));
+    if (result.isErr()) {
+      aRv.Throw(result.unwrapErr());
+      return nullptr;
+    }
+    return result.unwrap().forget();
+  };
+
+  // Step 5. Let cancelAlgorithm be the following steps, given reason:
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> CancelCallbackImpl(
+      JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason,
+      ErrorResult& aRv) override {
+    aRv.MightThrowJSException();
+
+    JS::Rooted<JSObject*> iteratorRecord(aCx, mIteratorRecordMaybeCrossRealm);
+    JSAutoRealm ar(aCx, iteratorRecord);
+
+    // Step 1. Let iterator be iteratorRecord.[[Iterator]].
+    JS::Rooted<JS::Value> iterator(aCx);
+    if (!JS::GetIteratorRecordIterator(aCx, iteratorRecord, &iterator)) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    // Step 2. Let returnMethod be GetMethod(iterator, "return").
+    JS::Rooted<JS::Value> returnMethod(aCx);
+    if (!JS::GetReturnMethod(aCx, iterator, &returnMethod)) {
+      // Step 3. If returnMethod is an abrupt completion, return a promise
+      // rejected with returnMethod.[[Value]].
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    // Step 4. If returnMethod.[[Value]] is undefined, return a promise resolved
+    // with undefined.
+    if (returnMethod.isUndefined()) {
+      return Promise::CreateResolvedWithUndefined(mGlobal, aRv);
+    }
+
+    // Step 5. Let returnResult be Call(returnMethod.[[Value]], iterator, «
+    // reason »).
+    JS::Rooted<JS::Value> returnResult(aCx);
+    if (!JS::Call(aCx, iterator, returnMethod,
+                  JS::HandleValueArray(aReason.Value()), &returnResult)) {
+      // Step 6. If returnResult is an abrupt completion, return a promise
+      // rejected with returnResult.[[Value]].
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    // Step 7. Let returnPromise be a promise resolved with
+    // returnResult.[[Value]].
+    RefPtr<Promise> returnPromise = Promise::CreateInfallible(mGlobal);
+    returnPromise->MaybeResolve(returnResult);
+
+    // Step 8. Return the result of reacting to returnPromise with the following
+    // fulfillment steps, given iterResult:
+    auto result = returnPromise->ThenWithCycleCollectedArgs(
+        [](JSContext* aCx, JS::Handle<JS::Value> aIterResult, ErrorResult& aRv)
+            MOZ_CAN_RUN_SCRIPT_FOR_DEFINITION -> already_AddRefed<Promise> {
+              // Step 8.1. If Type(iterResult) is not Object, throw a TypeError.
+              if (!aIterResult.isObject()) {
+                aRv.ThrowTypeError("return() returned a non-object value");
+                return nullptr;
+              }
+
+              // Step 8.2. Return undefined.
+              return nullptr;
+            });
+    if (result.isErr()) {
+      aRv.Throw(result.unwrapErr());
+      return nullptr;
+    }
+    return result.unwrap().forget();
+  };
+
+ protected:
+  ~ReadableStreamFromAlgorithms() override { mozilla::DropJSObjects(this); };
+
+ private:
+  // Virtually const, but are cycle collected
+  nsCOMPtr<nsIGlobalObject> mGlobal;
+  JS::Heap<JSObject*> mIteratorRecordMaybeCrossRealm;
+};
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED_WITH_JS_MEMBERS(
+    ReadableStreamFromAlgorithms, UnderlyingSourceAlgorithmsWrapper, (mGlobal),
+    (mIteratorRecordMaybeCrossRealm))
+NS_IMPL_ADDREF_INHERITED(ReadableStreamFromAlgorithms,
+                         UnderlyingSourceAlgorithmsWrapper)
+NS_IMPL_RELEASE_INHERITED(ReadableStreamFromAlgorithms,
+                          UnderlyingSourceAlgorithmsWrapper)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ReadableStreamFromAlgorithms)
+NS_INTERFACE_MAP_END_INHERITING(UnderlyingSourceAlgorithmsWrapper)
+
+// https://streams.spec.whatwg.org/#readable-stream-from-iterable
+static already_AddRefed<ReadableStream> MOZ_CAN_RUN_SCRIPT
+ReadableStreamFromIterable(JSContext* aCx, nsIGlobalObject* aGlobal,
+                           JS::Handle<JS::Value> aAsyncIterable,
+                           ErrorResult& aRv) {
+  aRv.MightThrowJSException();
+
+  // Step 1. Let stream be undefined. (not required)
+  // Step 2. Let iteratorRecord be ? GetIterator(asyncIterable, async).
+  JS::Rooted<JSObject*> iteratorRecord(
+      aCx, JS::GetIteratorObject(aCx, aAsyncIterable, true));
+  if (!iteratorRecord) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return nullptr;
+  }
+
+  // Steps 3-5. are in ReadableStreamFromAlgorithms.
+  auto algorithms =
+      MakeRefPtr<ReadableStreamFromAlgorithms>(aGlobal, iteratorRecord);
+
+  // Step 6. Set stream to ! CreateReadableStream(startAlgorithm, pullAlgorithm,
+  // cancelAlgorithm, 0).
+  // Step 7. Return stream.
+  return ReadableStream::CreateAbstract(aCx, aGlobal, algorithms,
+                                        mozilla::Some(0.0), nullptr, aRv);
+}
+
+/* static */
+already_AddRefed<ReadableStream> ReadableStream::From(
+    const GlobalObject& aGlobal, JS::Handle<JS::Value> aAsyncIterable,
+    ErrorResult& aRv) {
+  // Step 1. Return ? ReadableStreamFromIterable(asyncIterable).
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  return ReadableStreamFromIterable(aGlobal.Context(), global, aAsyncIterable,
+                                    aRv);
+}
+
+// Dealing with const this ptr is a pain, so just re-implement.
+// https://streams.spec.whatwg.org/#is-readable-stream-locked
+bool ReadableStream::Locked() const {
+  // Step 1 + 2.
+  return mReader;
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#initialize-readable-stream
+static void InitializeReadableStream(ReadableStream* aStream) {
+  // Step 1.
+  aStream->SetState(ReadableStream::ReaderState::Readable);
+
+  // Step 2.
+  aStream->SetReader(nullptr);
+  aStream->SetStoredError(JS::UndefinedHandleValue);
+
+  // Step 3.
+  aStream->SetDisturbed(false);
+}
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#create-readable-stream
+MOZ_CAN_RUN_SCRIPT
+already_AddRefed<ReadableStream> ReadableStream::CreateAbstract(
+    JSContext* aCx, nsIGlobalObject* aGlobal,
+    UnderlyingSourceAlgorithmsBase* aAlgorithms,
+    mozilla::Maybe<double> aHighWaterMark, QueuingStrategySize* aSizeAlgorithm,
+    ErrorResult& aRv) {
+  // Step 1. If highWaterMark was not passed, set it to 1.
+  double highWaterMark = aHighWaterMark.valueOr(1.0);
+
+  // Step 2. consumers of sizeAlgorithm
+  //         handle null algorithms correctly.
+  // Step 3.
+  MOZ_ASSERT(IsNonNegativeNumber(highWaterMark));
+  // Step 4.
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
+
+  // Step 5.
+  InitializeReadableStream(stream);
+
+  // Step 6.
+  RefPtr<ReadableStreamDefaultController> controller =
+      new ReadableStreamDefaultController(aGlobal);
+
+  // Step 7.
+  SetUpReadableStreamDefaultController(aCx, stream, controller, aAlgorithms,
+                                       highWaterMark, aSizeAlgorithm, aRv);
+
+  // Step 8.
+  return stream.forget();
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#readable-stream-close
+void ReadableStreamClose(JSContext* aCx, ReadableStream* aStream,
+                         ErrorResult& aRv) {
+  // Step 1.
+  MOZ_ASSERT(aStream->State() == ReadableStream::ReaderState::Readable);
+
+  // Step 2.
+  aStream->SetState(ReadableStream::ReaderState::Closed);
+
+  // Step 3.
+  ReadableStreamGenericReader* reader = aStream->GetReader();
+
+  // Step 4.
+  if (!reader) {
+    return;
+  }
+
+  // Step 5.
+  reader->ClosedPromise()->MaybeResolveWithUndefined();
+
+  // Step 6.
+  if (reader->IsDefault()) {
+    // Step 6.1. Let readRequests be reader.[[readRequests]].
+    // Move LinkedList out of DefaultReader onto stack to avoid the potential
+    // for concurrent modification, which could invalidate the iterator.
+    //
+    // See https://bugs.chromium.org/p/chromium/issues/detail?id=1045874 as an
+    // example of the kind of issue that could occur.
+    LinkedList<RefPtr<ReadRequest>> readRequests =
+        std::move(reader->AsDefault()->ReadRequests());
+
+    // Step 6.2. Set reader.[[readRequests]] to an empty list.
+    // Note: The std::move already cleared this anyway.
+    reader->AsDefault()->ReadRequests().clear();
+
+    // Step 6.3. For each readRequest of readRequests,
+    // Drain the local list and destroy elements along the way.
+    while (RefPtr<ReadRequest> readRequest = readRequests.popFirst()) {
+      // Step 6.3.1. Perform readRequest’s close steps.
+      readRequest->CloseSteps(aCx, aRv);
+      if (aRv.Failed()) {
+        return;
+      }
+    }
+  }
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-cancel
+already_AddRefed<Promise> ReadableStreamCancel(JSContext* aCx,
+                                               ReadableStream* aStream,
+                                               JS::Handle<JS::Value> aError,
+                                               ErrorResult& aRv) {
+  // Step 1.
+  aStream->SetDisturbed(true);
+
+  // Step 2.
+  if (aStream->State() == ReadableStream::ReaderState::Closed) {
+    RefPtr<Promise> promise =
+        Promise::CreateInfallible(aStream->GetParentObject());
+    promise->MaybeResolveWithUndefined();
+    return promise.forget();
+  }
+
+  // Step 3.
+  if (aStream->State() == ReadableStream::ReaderState::Errored) {
+    JS::Rooted<JS::Value> storedError(aCx, aStream->StoredError());
+    return Promise::CreateRejected(aStream->GetParentObject(), storedError,
+                                   aRv);
+  }
+
+  // Step 4.
+  ReadableStreamClose(aCx, aStream, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 5.
+  ReadableStreamGenericReader* reader = aStream->GetReader();
+
+  // Step 6.
+  if (reader && reader->IsBYOB()) {
+    // Step 6.1. Let readIntoRequests be reader.[[readIntoRequests]].
+    LinkedList<RefPtr<ReadIntoRequest>> readIntoRequests =
+        std::move(reader->AsBYOB()->ReadIntoRequests());
+
+    // Step 6.2. Set reader.[[readIntoRequests]] to an empty list.
+    // Note: The std::move already cleared this anyway.
+    reader->AsBYOB()->ReadIntoRequests().clear();
+
+    // Step 6.3. For each readIntoRequest of readIntoRequests,
+    while (RefPtr<ReadIntoRequest> readIntoRequest =
+               readIntoRequests.popFirst()) {
+      // Step 6.3.1.Perform readIntoRequest’s close steps, given undefined.
+      readIntoRequest->CloseSteps(aCx, JS::UndefinedHandleValue, aRv);
+      if (aRv.Failed()) {
+        return nullptr;
+      }
+    }
+  }
+
+  // Step 7.
+  RefPtr<ReadableStreamController> controller(aStream->Controller());
+  RefPtr<Promise> sourceCancelPromise =
+      controller->CancelSteps(aCx, aError, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 8.
+  RefPtr<Promise> promise =
+      Promise::CreateInfallible(sourceCancelPromise->GetParentObject());
+
+  // ThenWithCycleCollectedArgs will carry promise, keeping it alive until the
+  // callback executes.
+  Result<RefPtr<Promise>, nsresult> returnResult =
+      sourceCancelPromise->ThenWithCycleCollectedArgs(
+          [](JSContext*, JS::Handle<JS::Value>, ErrorResult&,
+             RefPtr<Promise> newPromise) {
+            newPromise->MaybeResolveWithUndefined();
+            return newPromise.forget();
+          },
+          promise);
+
+  if (returnResult.isErr()) {
+    aRv.Throw(returnResult.unwrapErr());
+    return nullptr;
+  }
+
+  return returnResult.unwrap().forget();
+}
+
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#rs-cancel
+already_AddRefed<Promise> ReadableStream::Cancel(JSContext* aCx,
+                                                 JS::Handle<JS::Value> aReason,
+                                                 ErrorResult& aRv) {
+  // Step 1. If ! IsReadableStreamLocked(this) is true,
+  // return a promise rejected with a TypeError exception.
+  if (Locked()) {
+    aRv.ThrowTypeError("Cannot cancel a stream locked by a reader.");
+    return nullptr;
+  }
+
+  // Step 2. Return ! ReadableStreamCancel(this, reason).
+  RefPtr<ReadableStream> thisRefPtr = this;
+  return ReadableStreamCancel(aCx, thisRefPtr, aReason, aRv);
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#acquire-readable-stream-reader
+already_AddRefed<ReadableStreamDefaultReader>
+AcquireReadableStreamDefaultReader(ReadableStream* aStream, ErrorResult& aRv) {
+  // Step 1.
+  RefPtr<ReadableStreamDefaultReader> reader =
+      new ReadableStreamDefaultReader(aStream->GetParentObject());
+
+  // Step 2.
+  SetUpReadableStreamDefaultReader(reader, aStream, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 3.
+  return reader.forget();
+}
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#rs-get-reader
+void ReadableStream::GetReader(const ReadableStreamGetReaderOptions& aOptions,
+                               OwningReadableStreamReader& resultReader,
+                               ErrorResult& aRv) {
+  // Step 1. If options["mode"] does not exist,
+  // return ? AcquireReadableStreamDefaultReader(this).
+  if (!aOptions.mMode.WasPassed()) {
+    RefPtr<ReadableStreamDefaultReader> defaultReader =
+        AcquireReadableStreamDefaultReader(this, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+    resultReader.SetAsReadableStreamDefaultReader() = defaultReader;
+    return;
+  }
+
+  // Step 2. Assert: options["mode"] is "byob".
+  MOZ_ASSERT(aOptions.mMode.Value() == ReadableStreamReaderMode::Byob);
+
+  // Step 3. Return ? AcquireReadableStreamBYOBReader(this).
+  RefPtr<ReadableStreamBYOBReader> byobReader =
+      AcquireReadableStreamBYOBReader(this, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+  resultReader.SetAsReadableStreamBYOBReader() = byobReader;
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#is-readable-stream-locked
+bool IsReadableStreamLocked(ReadableStream* aStream) {
+  // Step 1 + 2.
+  return aStream->Locked();
+}
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#rs-pipe-through
+MOZ_CAN_RUN_SCRIPT already_AddRefed<ReadableStream> ReadableStream::PipeThrough(
+    const ReadableWritablePair& aTransform, const StreamPipeOptions& aOptions,
+    ErrorResult& aRv) {
+  // Step 1: If ! IsReadableStreamLocked(this) is true, throw a TypeError
+  // exception.
+  if (IsReadableStreamLocked(this)) {
+    aRv.ThrowTypeError("Cannot pipe from a locked stream.");
+    return nullptr;
+  }
+
+  // Step 2: If ! IsWritableStreamLocked(transform["writable"]) is true, throw a
+  // TypeError exception.
+  if (IsWritableStreamLocked(aTransform.mWritable)) {
+    aRv.ThrowTypeError("Cannot pipe to a locked stream.");
+    return nullptr;
+  }
+
+  // Step 3: Let signal be options["signal"] if it exists, or undefined
+  // otherwise.
+  RefPtr<AbortSignal> signal =
+      aOptions.mSignal.WasPassed() ? &aOptions.mSignal.Value() : nullptr;
+
+  // Step 4: Let promise be ! ReadableStreamPipeTo(this, transform["writable"],
+  // options["preventClose"], options["preventAbort"], options["preventCancel"],
+  // signal).
+  RefPtr<WritableStream> writable = aTransform.mWritable;
+  RefPtr<Promise> promise = ReadableStreamPipeTo(
+      this, writable, aOptions.mPreventClose, aOptions.mPreventAbort,
+      aOptions.mPreventCancel, signal, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 5: Set promise.[[PromiseIsHandled]] to true.
+  MOZ_ALWAYS_TRUE(promise->SetAnyPromiseIsHandled());
+
+  // Step 6: Return transform["readable"].
+  return do_AddRef(aTransform.mReadable.get());
+};
+
+namespace streams_abstract {
+
+// https://streams.spec.whatwg.org/#readable-stream-get-num-read-requests
+double ReadableStreamGetNumReadRequests(ReadableStream* aStream) {
+  // Step 1.
+  MOZ_ASSERT(ReadableStreamHasDefaultReader(aStream));
+
+  // Step 2.
+  return double(aStream->GetDefaultReader()->ReadRequests().length());
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-error
+void ReadableStreamError(JSContext* aCx, ReadableStream* aStream,
+                         JS::Handle<JS::Value> aValue, ErrorResult& aRv) {
+  // Step 1.
+  MOZ_ASSERT(aStream->State() == ReadableStream::ReaderState::Readable);
+
+  // Step 2.
+  aStream->SetState(ReadableStream::ReaderState::Errored);
+
+  // Step 3.
+  aStream->SetStoredError(aValue);
+
+  // Step 4.
+  ReadableStreamGenericReader* reader = aStream->GetReader();
+
+  // Step 5.
+  if (!reader) {
+    return;
+  }
+
+  // Step 6.
+  reader->ClosedPromise()->MaybeReject(aValue);
+
+  // Step 7.
+  reader->ClosedPromise()->SetSettledPromiseIsHandled();
+
+  // Step 8.
+  if (reader->IsDefault()) {
+    // Step 8.1. Perform ! ReadableStreamDefaultReaderErrorReadRequests(reader,
+    // e).
+    RefPtr<ReadableStreamDefaultReader> defaultReader = reader->AsDefault();
+    ReadableStreamDefaultReaderErrorReadRequests(aCx, defaultReader, aValue,
+                                                 aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  } else {
+    // Step 9. Otherwise,
+    // Step 9.1. Assert: reader implements ReadableStreamBYOBReader.
+    MOZ_ASSERT(reader->IsBYOB());
+
+    // Step 9.2. Perform ! ReadableStreamBYOBReaderErrorReadIntoRequests(reader,
+    // e).
+    RefPtr<ReadableStreamBYOBReader> byobReader = reader->AsBYOB();
+    ReadableStreamBYOBReaderErrorReadIntoRequests(aCx, byobReader, aValue, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  }
+}
+
+// https://streams.spec.whatwg.org/#rs-default-controller-close
+void ReadableStreamFulfillReadRequest(JSContext* aCx, ReadableStream* aStream,
+                                      JS::Handle<JS::Value> aChunk, bool aDone,
+                                      ErrorResult& aRv) {
+  // Step 1.
+  MOZ_ASSERT(ReadableStreamHasDefaultReader(aStream));
+
+  // Step 2.
+  ReadableStreamDefaultReader* reader = aStream->GetDefaultReader();
+
+  // Step 3.
+  MOZ_ASSERT(!reader->ReadRequests().isEmpty());
+
+  // Step 4+5.
+  RefPtr<ReadRequest> readRequest = reader->ReadRequests().popFirst();
+
+  // Step 6.
+  if (aDone) {
+    readRequest->CloseSteps(aCx, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+  }
+
+  // Step 7.
+  readRequest->ChunkSteps(aCx, aChunk, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-add-read-request
+void ReadableStreamAddReadRequest(ReadableStream* aStream,
+                                  ReadRequest* aReadRequest) {
+  // Step 1.
+  MOZ_ASSERT(aStream->GetReader()->IsDefault());
+  // Step 2.
+  MOZ_ASSERT(aStream->State() == ReadableStream::ReaderState::Readable);
+  // Step 3.
+  aStream->GetDefaultReader()->ReadRequests().insertBack(aReadRequest);
+}
+
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#abstract-opdef-readablestreamdefaulttee
+// Step 14, 15
+MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise>
+ReadableStreamDefaultTeeSourceAlgorithms::CancelCallback(
+    JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason,
+    ErrorResult& aRv) {
+  // Step 1.
+  mTeeState->SetCanceled(mBranch, true);
+
+  // Step 2.
+  mTeeState->SetReason(mBranch, aReason.Value());
+
+  // Step 3.
+
+  if (mTeeState->Canceled(OtherTeeBranch(mBranch))) {
+    // Step 3.1
+
+    JS::Rooted<JSObject*> compositeReason(aCx, JS::NewArrayObject(aCx, 2));
+    if (!compositeReason) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    JS::Rooted<JS::Value> reason1(aCx, mTeeState->Reason1());
+    if (!JS_SetElement(aCx, compositeReason, 0, reason1)) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    JS::Rooted<JS::Value> reason2(aCx, mTeeState->Reason2());
+    if (!JS_SetElement(aCx, compositeReason, 1, reason2)) {
+      aRv.StealExceptionFromJSContext(aCx);
+      return nullptr;
+    }
+
+    // Step 3.2
+    JS::Rooted<JS::Value> compositeReasonValue(
+        aCx, JS::ObjectValue(*compositeReason));
+    RefPtr<ReadableStream> stream(mTeeState->GetStream());
+    RefPtr<Promise> cancelResult =
+        ReadableStreamCancel(aCx, stream, compositeReasonValue, aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+
+    // Step 3.3
+    mTeeState->CancelPromise()->MaybeResolve(cancelResult);
+  }
+
+  // Step 4.
+  return do_AddRef(mTeeState->CancelPromise());
+}
+
+// https://streams.spec.whatwg.org/#abstract-opdef-readablestreamdefaulttee
+MOZ_CAN_RUN_SCRIPT
+static void ReadableStreamDefaultTee(JSContext* aCx, ReadableStream* aStream,
+                                     bool aCloneForBranch2,
+                                     nsTArray<RefPtr<ReadableStream>>& aResult,
+                                     ErrorResult& aRv) {
+  // Step 1. Implicit.
+  // Step 2. Implicit.
+
+  // Steps 3-12 are contained in the construction of Tee State.
+  RefPtr<TeeState> teeState = TeeState::Create(aStream, aCloneForBranch2, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 13 - 16
+  auto branch1Algorithms = MakeRefPtr<ReadableStreamDefaultTeeSourceAlgorithms>(
+      teeState, TeeBranch::Branch1);
+  auto branch2Algorithms = MakeRefPtr<ReadableStreamDefaultTeeSourceAlgorithms>(
+      teeState, TeeBranch::Branch2);
+
+  // Step 17.
+  nsCOMPtr<nsIGlobalObject> global(
+      do_AddRef(teeState->GetStream()->GetParentObject()));
+  teeState->SetBranch1(ReadableStream::CreateAbstract(
+      aCx, global, branch1Algorithms, mozilla::Nothing(), nullptr, aRv));
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 18.
+  teeState->SetBranch2(ReadableStream::CreateAbstract(
+      aCx, global, branch2Algorithms, mozilla::Nothing(), nullptr, aRv));
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 19.
+  teeState->GetReader()->ClosedPromise()->AddCallbacksWithCycleCollectedArgs(
+      [](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
+         TeeState* aTeeState) {},
+      [](JSContext* aCx, JS::Handle<JS::Value> aReason, ErrorResult& aRv,
+         TeeState* aTeeState) {
+        // Step 19.1.
+        ReadableStreamDefaultControllerError(
+            aCx, aTeeState->Branch1()->DefaultController(), aReason, aRv);
+        if (aRv.Failed()) {
+          return;
+        }
+
+        // Step 19.2
+        ReadableStreamDefaultControllerError(
+            aCx, aTeeState->Branch2()->DefaultController(), aReason, aRv);
+        if (aRv.Failed()) {
+          return;
+        }
+
+        // Step 19.3
+        if (!aTeeState->Canceled1() || !aTeeState->Canceled2()) {
+          aTeeState->CancelPromise()->MaybeResolveWithUndefined();
+        }
+      },
+      RefPtr(teeState));
+
+  // Step 20.
+  aResult.AppendElement(teeState->Branch1());
+  aResult.AppendElement(teeState->Branch2());
+}
+
+// https://streams.spec.whatwg.org/#rs-pipe-to
+already_AddRefed<Promise> ReadableStream::PipeTo(
+    WritableStream& aDestination, const StreamPipeOptions& aOptions,
+    ErrorResult& aRv) {
+  // Step 1. If !IsReadableStreamLocked(this) is true, return a promise rejected
+  // with a TypeError exception.
+  if (IsReadableStreamLocked(this)) {
+    aRv.ThrowTypeError("Cannot pipe from a locked stream.");
+    return nullptr;
+  }
+
+  // Step 2. If !IsWritableStreamLocked(destination) is true, return a promise
+  //         rejected with a TypeError exception.
+  if (IsWritableStreamLocked(&aDestination)) {
+    aRv.ThrowTypeError("Cannot pipe to a locked stream.");
+    return nullptr;
+  }
+
+  // Step 3. Let signal be options["signal"] if it exists, or undefined
+  // otherwise.
+  RefPtr<AbortSignal> signal =
+      aOptions.mSignal.WasPassed() ? &aOptions.mSignal.Value() : nullptr;
+
+  // Step 4. Return ! ReadableStreamPipeTo(this, destination,
+  // options["preventClose"], options["preventAbort"], options["preventCancel"],
+  // signal).
+  return ReadableStreamPipeTo(this, &aDestination, aOptions.mPreventClose,
+                              aOptions.mPreventAbort, aOptions.mPreventCancel,
+                              signal, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readable-stream-tee
+MOZ_CAN_RUN_SCRIPT
+static void ReadableStreamTee(JSContext* aCx, ReadableStream* aStream,
+                              bool aCloneForBranch2,
+                              nsTArray<RefPtr<ReadableStream>>& aResult,
+                              ErrorResult& aRv) {
+  // Step 1. Implicit.
+  // Step 2. Implicit.
+  // Step 3.
+  if (aStream->Controller()->IsByte()) {
+    ReadableByteStreamTee(aCx, aStream, aResult, aRv);
+    return;
+  }
+  // Step 4.
+  ReadableStreamDefaultTee(aCx, aStream, aCloneForBranch2, aResult, aRv);
+}
+
+void ReadableStream::Tee(JSContext* aCx,
+                         nsTArray<RefPtr<ReadableStream>>& aResult,
+                         ErrorResult& aRv) {
+  ReadableStreamTee(aCx, this, false, aResult, aRv);
+}
+
+void ReadableStream::IteratorData::Traverse(
+    nsCycleCollectionTraversalCallback& cb) {
+  ReadableStream::IteratorData* tmp = this;
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mReader);
+}
+void ReadableStream::IteratorData::Unlink() {
+  ReadableStream::IteratorData* tmp = this;
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mReader);
+}
+
+// https://streams.spec.whatwg.org/#rs-get-iterator
+void ReadableStream::InitAsyncIteratorData(
+    IteratorData& aData, Iterator::IteratorType aType,
+    const ReadableStreamIteratorOptions& aOptions, ErrorResult& aRv) {
+  // Step 1. Let reader be ? AcquireReadableStreamDefaultReader(stream).
+  RefPtr<ReadableStreamDefaultReader> reader =
+      AcquireReadableStreamDefaultReader(this, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 2. Set iterator’s reader to reader.
+  aData.mReader = reader;
+
+  // Step 3. Let preventCancel be args[0]["preventCancel"].
+  // Step 4. Set iterator’s prevent cancel to preventCancel.
+  aData.mPreventCancel = aOptions.mPreventCancel;
+}
+
+// https://streams.spec.whatwg.org/#rs-asynciterator-prototype-next
+// Step 4.
+struct IteratorReadRequest : public ReadRequest {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(IteratorReadRequest, ReadRequest)
+
+  RefPtr<Promise> mPromise;
+  RefPtr<ReadableStreamDefaultReader> mReader;
+
+  explicit IteratorReadRequest(Promise* aPromise,
+                               ReadableStreamDefaultReader* aReader)
+      : mPromise(aPromise), mReader(aReader) {}
+
+  // chunk steps, given chunk
+  void ChunkSteps(JSContext* aCx, JS::Handle<JS::Value> aChunk,
+                  ErrorResult& aRv) override {
+    // Step 1. Resolve promise with chunk.
+    mPromise->MaybeResolve(aChunk);
+  }
+
+  // close steps
+  void CloseSteps(JSContext* aCx, ErrorResult& aRv) override {
+    // Step 1. Perform ! ReadableStreamDefaultReaderRelease(reader).
+    ReadableStreamDefaultReaderRelease(aCx, mReader, aRv);
+    if (aRv.Failed()) {
+      mPromise->MaybeRejectWithUndefined();
+      return;
+    }
+
+    // Step 2. Resolve promise with end of iteration.
+    iterator_utils::ResolvePromiseForFinished(mPromise);
+  }
+
+  // error steps, given e
+  void ErrorSteps(JSContext* aCx, JS::Handle<JS::Value> aError,
+                  ErrorResult& aRv) override {
+    // Step 1. Perform ! ReadableStreamDefaultReaderRelease(reader).
+    ReadableStreamDefaultReaderRelease(aCx, mReader, aRv);
+    if (aRv.Failed()) {
+      mPromise->MaybeRejectWithUndefined();
+      return;
+    }
+
+    // Step 2. Reject promise with e.
+    mPromise->MaybeReject(aError);
+  }
+
+ protected:
+  virtual ~IteratorReadRequest() = default;
+};
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(IteratorReadRequest, ReadRequest, mPromise,
+                                   mReader)
+
+NS_IMPL_ADDREF_INHERITED(IteratorReadRequest, ReadRequest)
+NS_IMPL_RELEASE_INHERITED(IteratorReadRequest, ReadRequest)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(IteratorReadRequest)
+NS_INTERFACE_MAP_END_INHERITING(ReadRequest)
+
+// https://streams.spec.whatwg.org/#rs-asynciterator-prototype-next
+already_AddRefed<Promise> ReadableStream::GetNextIterationResult(
+    Iterator* aIterator, ErrorResult& aRv) {
+  // Step 1. Let reader be iterator’s reader.
+  RefPtr<ReadableStreamDefaultReader> reader = aIterator->Data().mReader;
+
+  // Step 2. Assert: reader.[[stream]] is not undefined.
+  MOZ_ASSERT(reader->GetStream());
+
+  // Step 3. Let promise be a new promise.
+  RefPtr<Promise> promise = Promise::CreateInfallible(GetParentObject());
+
+  // Step 4. Let readRequest be a new read request with the following items:
+  RefPtr<ReadRequest> request = new IteratorReadRequest(promise, reader);
+
+  // Step 5. Perform ! ReadableStreamDefaultReaderRead(this, readRequest).
+  AutoJSAPI jsapi;
+  if (!jsapi.Init(mGlobal)) {
+    aRv.ThrowUnknownError("Internal error");
+    return nullptr;
+  }
+
+  ReadableStreamDefaultReaderRead(jsapi.cx(), reader, request, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 6. Return promise.
+  return promise.forget();
+}
+
+// https://streams.spec.whatwg.org/#rs-asynciterator-prototype-return
+already_AddRefed<Promise> ReadableStream::IteratorReturn(
+    JSContext* aCx, Iterator* aIterator, JS::Handle<JS::Value> aValue,
+    ErrorResult& aRv) {
+  // Step 1. Let reader be iterator’s reader.
+  RefPtr<ReadableStreamDefaultReader> reader = aIterator->Data().mReader;
+
+  // Step 2. Assert: reader.[[stream]] is not undefined.
+  MOZ_ASSERT(reader->GetStream());
+
+  // Step 3. Assert: reader.[[readRequests]] is empty, as the async iterator
+  // machinery guarantees that any previous calls to next() have settled before
+  // this is called.
+  MOZ_ASSERT(reader->ReadRequests().isEmpty());
+
+  // Step 4. If iterator’s prevent cancel is false:
+  if (!aIterator->Data().mPreventCancel) {
+    // Step 4.1. Let result be ! ReadableStreamReaderGenericCancel(reader, arg).
+    RefPtr<ReadableStream> stream(reader->GetStream());
+    RefPtr<Promise> result = ReadableStreamCancel(aCx, stream, aValue, aRv);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+
+    MOZ_DIAGNOSTIC_ASSERT(
+        reader->GetStream(),
+        "We shouldn't have a null stream here (bug 1821169).");
+    if (!reader->GetStream()) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    // Step 4.2. Perform ! ReadableStreamDefaultReaderRelease(reader).
+    ReadableStreamDefaultReaderRelease(aCx, reader, aRv);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+
+    // Step 4.3. Return result.
+    return result.forget();
+  }
+
+  // Step 5. Perform ! ReadableStreamDefaultReaderRelease(reader).
+  ReadableStreamDefaultReaderRelease(aCx, reader, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  // Step 6. Return a promise resolved with undefined.
+  return Promise::CreateResolvedWithUndefined(GetParentObject(), aRv);
+}
+
+namespace streams_abstract {
+// https://streams.spec.whatwg.org/#readable-stream-add-read-into-request
+void ReadableStreamAddReadIntoRequest(ReadableStream* aStream,
+                                      ReadIntoRequest* aReadIntoRequest) {
+  // Step 1. Assert: stream.[[reader]] implements ReadableStreamBYOBReader.
+  MOZ_ASSERT(aStream->GetReader()->IsBYOB());
+
+  // Step 2. Assert: stream.[[state]] is "readable" or "closed".
+  MOZ_ASSERT(aStream->State() == ReadableStream::ReaderState::Readable ||
+             aStream->State() == ReadableStream::ReaderState::Closed);
+
+  // Step 3. Append readRequest to stream.[[reader]].[[readIntoRequests]].
+  aStream->GetReader()->AsBYOB()->ReadIntoRequests().insertBack(
+      aReadIntoRequest);
+}
+}  // namespace streams_abstract
+
+// https://streams.spec.whatwg.org/#abstract-opdef-createreadablebytestream
+already_AddRefed<ReadableStream> ReadableStream::CreateByteAbstract(
+    JSContext* aCx, nsIGlobalObject* aGlobal,
+    UnderlyingSourceAlgorithmsBase* aAlgorithms, ErrorResult& aRv) {
+  // Step 1. Let stream be a new ReadableStream.
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
+
+  // Step 2. Perform ! InitializeReadableStream(stream).
+  InitializeReadableStream(stream);
+
+  // Step 3. Let controller be a new ReadableByteStreamController.
+  RefPtr<ReadableByteStreamController> controller =
+      new ReadableByteStreamController(aGlobal);
+
+  // Step 4. Perform ? SetUpReadableByteStreamController(stream, controller,
+  // startAlgorithm, pullAlgorithm, cancelAlgorithm, 0, undefined).
+  SetUpReadableByteStreamController(aCx, stream, controller, aAlgorithms, 0,
+                                    mozilla::Nothing(), aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Return stream.
+  return stream.forget();
+}
+
+// https://streams.spec.whatwg.org/#readablestream-set-up
+// (except this instead creates a new ReadableStream rather than accepting an
+// existing instance)
+// _BOUNDARY because `aAlgorithms->StartCallback` (called by
+// SetUpReadableStreamDefaultController below) should not be able to run script
+// in this case.
+MOZ_CAN_RUN_SCRIPT_BOUNDARY already_AddRefed<ReadableStream>
+ReadableStream::CreateNative(JSContext* aCx, nsIGlobalObject* aGlobal,
+                             UnderlyingSourceAlgorithmsWrapper& aAlgorithms,
+                             mozilla::Maybe<double> aHighWaterMark,
+                             QueuingStrategySize* aSizeAlgorithm,
+                             ErrorResult& aRv) {
+  // an optional number highWaterMark (default 1)
+  double highWaterMark = aHighWaterMark.valueOr(1);
+  // and if given, highWaterMark must be a non-negative, non-NaN number.
+  MOZ_ASSERT(IsNonNegativeNumber(highWaterMark));
+
+  // Step 1: Let startAlgorithm be an algorithm that returns undefined.
+  // Step 2: Let pullAlgorithmWrapper be an algorithm that runs these steps:
+  // Step 3: Let cancelAlgorithmWrapper be an algorithm that runs these steps:
+  // (Done by UnderlyingSourceAlgorithmsWrapper)
+
+  // Step 4: If sizeAlgorithm was not given, then set it to an algorithm that
+  // returns 1. (Callers will treat nullptr as such, see
+  // ReadableStream::Constructor for details)
+
+  // Step 5: Perform ! InitializeReadableStream(stream).
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
+
+  // Step 6: Let controller be a new ReadableStreamDefaultController.
+  auto controller = MakeRefPtr<ReadableStreamDefaultController>(aGlobal);
+
+  // Step 7: Perform ! SetUpReadableStreamDefaultController(stream, controller,
+  // startAlgorithm, pullAlgorithmWrapper, cancelAlgorithmWrapper,
+  // highWaterMark, sizeAlgorithm).
+  SetUpReadableStreamDefaultController(aCx, stream, controller, &aAlgorithms,
+                                       highWaterMark, aSizeAlgorithm, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  return stream.forget();
+}
+
+// https://streams.spec.whatwg.org/#readablestream-set-up-with-byte-reading-support
+// _BOUNDARY because `aAlgorithms->StartCallback` (called by
+// SetUpReadableByteStreamController below) should not be able to run script in
+// this case.
+MOZ_CAN_RUN_SCRIPT_BOUNDARY void ReadableStream::SetUpByteNative(
+    JSContext* aCx, UnderlyingSourceAlgorithmsWrapper& aAlgorithms,
+    mozilla::Maybe<double> aHighWaterMark, ErrorResult& aRv) {
+  // an optional number highWaterMark (default 0)
+  double highWaterMark = aHighWaterMark.valueOr(0);
+  // and if given, highWaterMark must be a non-negative, non-NaN number.
+  MOZ_ASSERT(IsNonNegativeNumber(highWaterMark));
+
+  // Step 1: Let startAlgorithm be an algorithm that returns undefined.
+  // Step 2: Let pullAlgorithmWrapper be an algorithm that runs these steps:
+  // Step 3: Let cancelAlgorithmWrapper be an algorithm that runs these steps:
+  // (Done by UnderlyingSourceAlgorithmsWrapper)
+
+  // Step 4: Perform ! InitializeReadableStream(stream).
+  // (Covered by constructor)
+
+  // Step 5: Let controller be a new ReadableByteStreamController.
+  auto controller = MakeRefPtr<ReadableByteStreamController>(GetParentObject());
+
+  // Step 6: Perform ! SetUpReadableByteStreamController(stream, controller,
+  // startAlgorithm, pullAlgorithmWrapper, cancelAlgorithmWrapper,
+  // highWaterMark, undefined).
+  SetUpReadableByteStreamController(aCx, this, controller, &aAlgorithms,
+                                    highWaterMark, Nothing(), aRv);
+}
+
+already_AddRefed<ReadableStream> ReadableStream::CreateByteNative(
+    JSContext* aCx, nsIGlobalObject* aGlobal,
+    UnderlyingSourceAlgorithmsWrapper& aAlgorithms,
+    mozilla::Maybe<double> aHighWaterMark, ErrorResult& aRv) {
+  RefPtr<ReadableStream> stream =
+      new ReadableStream(aGlobal, HoldDropJSObjectsCaller::Implicit);
+  stream->SetUpByteNative(aCx, aAlgorithms, aHighWaterMark, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  return stream.forget();
+}
+
+// https://streams.spec.whatwg.org/#readablestream-close
+void ReadableStream::CloseNative(JSContext* aCx, ErrorResult& aRv) {
+  MOZ_ASSERT_IF(mController->GetAlgorithms(),
+                mController->GetAlgorithms()->IsNative());
+  // Step 1: If stream.[[controller]] implements ReadableByteStreamController,
+  if (mController->IsByte()) {
+    RefPtr<ReadableByteStreamController> controller = mController->AsByte();
+
+    // Step 1.1: Perform !
+    // ReadableByteStreamControllerClose(stream.[[controller]]).
+    ReadableByteStreamControllerClose(aCx, controller, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    // Step 1.2: If stream.[[controller]].[[pendingPullIntos]] is not empty,
+    // perform ! ReadableByteStreamControllerRespond(stream.[[controller]], 0).
+    if (!controller->PendingPullIntos().isEmpty()) {
+      ReadableByteStreamControllerRespond(aCx, controller, 0, aRv);
+    }
+    return;
+  }
+
+  // Step 2: Otherwise, perform !
+  // ReadableStreamDefaultControllerClose(stream.[[controller]]).
+  RefPtr<ReadableStreamDefaultController> controller = mController->AsDefault();
+  ReadableStreamDefaultControllerClose(aCx, controller, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readablestream-error
+void ReadableStream::ErrorNative(JSContext* aCx, JS::Handle<JS::Value> aError,
+                                 ErrorResult& aRv) {
+  // Step 1: If stream.[[controller]] implements ReadableByteStreamController,
+  // then perform ! ReadableByteStreamControllerError(stream.[[controller]], e).
+  if (mController->IsByte()) {
+    ReadableByteStreamControllerError(mController->AsByte(), aError, aRv);
+    return;
+  }
+  // Step 2: Otherwise, perform !
+  // ReadableStreamDefaultControllerError(stream.[[controller]], e).
+  ReadableStreamDefaultControllerError(aCx, mController->AsDefault(), aError,
+                                       aRv);
+}
+
+// https://streams.spec.whatwg.org/#readablestream-current-byob-request-view
+static void CurrentBYOBRequestView(JSContext* aCx,
+                                   ReadableByteStreamController& aController,
+                                   JS::MutableHandle<JSObject*> aRetVal,
+                                   ErrorResult& aRv) {
+  // Step 1. Assert: stream.[[controller]] implements
+  // ReadableByteStreamController. (implicit)
+
+  // Step 2: Let byobRequest be !
+  // ReadableByteStreamControllerGetBYOBRequest(stream.[[controller]]).
+  RefPtr<ReadableStreamBYOBRequest> byobRequest =
+      ReadableByteStreamControllerGetBYOBRequest(aCx, &aController, aRv);
+  // Step 3: If byobRequest is null, then return null.
+  if (!byobRequest) {
+    aRetVal.set(nullptr);
+    return;
+  }
+  // Step 4: Return byobRequest.[[view]].
+  byobRequest->GetView(aCx, aRetVal);
+}
+
+static bool HasSameBufferView(JSContext* aCx, JS::Handle<JSObject*> aX,
+                              JS::Handle<JSObject*> aY, ErrorResult& aRv) {
+  bool isShared;
+  JS::Rooted<JSObject*> viewedBufferX(
+      aCx, JS_GetArrayBufferViewBuffer(aCx, aX, &isShared));
+  if (!viewedBufferX) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return false;
+  }
+
+  JS::Rooted<JSObject*> viewedBufferY(
+      aCx, JS_GetArrayBufferViewBuffer(aCx, aY, &isShared));
+  if (!viewedBufferY) {
+    aRv.StealExceptionFromJSContext(aCx);
+    return false;
+  }
+
+  return viewedBufferX == viewedBufferY;
+}
+
+// https://streams.spec.whatwg.org/#readablestream-enqueue
+void ReadableStream::EnqueueNative(JSContext* aCx, JS::Handle<JS::Value> aChunk,
+                                   ErrorResult& aRv) {
+  MOZ_ASSERT(mController->GetAlgorithms()->IsNative());
+
+  // Step 1: If stream.[[controller]] implements
+  // ReadableStreamDefaultController,
+  if (mController->IsDefault()) {
+    // Step 1.1: Perform !
+    // ReadableStreamDefaultControllerEnqueue(stream.[[controller]], chunk).
+    RefPtr<ReadableStreamDefaultController> controller =
+        mController->AsDefault();
+    ReadableStreamDefaultControllerEnqueue(aCx, controller, aChunk, aRv);
+    return;
+  }
+
+  // Step 2.1: Assert: stream.[[controller]] implements
+  // ReadableByteStreamController.
+  MOZ_ASSERT(mController->IsByte());
+  RefPtr<ReadableByteStreamController> controller = mController->AsByte();
+
+  // Step 2.2: Assert: chunk is an ArrayBufferView.
+  MOZ_ASSERT(aChunk.isObject() &&
+             JS_IsArrayBufferViewObject(&aChunk.toObject()));
+  JS::Rooted<JSObject*> chunk(aCx, &aChunk.toObject());
+
+  // Step 3: Let byobView be the current BYOB request view for stream.
+  JS::Rooted<JSObject*> byobView(aCx);
+  CurrentBYOBRequestView(aCx, *controller, &byobView, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 4: If byobView is non-null, and chunk.[[ViewedArrayBuffer]] is
+  // byobView.[[ViewedArrayBuffer]], then:
+  if (byobView && HasSameBufferView(aCx, chunk, byobView, aRv)) {
+    // Step 4.1: Assert: chunk.[[ByteOffset]] is byobView.[[ByteOffset]].
+    MOZ_ASSERT(JS_GetArrayBufferViewByteOffset(chunk) ==
+               JS_GetArrayBufferViewByteOffset(byobView));
+    // Step 4.2: Assert: chunk.[[ByteLength]] ≤ byobView.[[ByteLength]].
+    MOZ_ASSERT(JS_GetArrayBufferViewByteLength(chunk) <=
+               JS_GetArrayBufferViewByteLength(byobView));
+    // Step 4.3: Perform ?
+    // ReadableByteStreamControllerRespond(stream.[[controller]],
+    // chunk.[[ByteLength]]).
+    ReadableByteStreamControllerRespond(
+        aCx, controller, JS_GetArrayBufferViewByteLength(chunk), aRv);
+    return;
+  }
+
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Step 5: Otherwise, perform ?
+  // ReadableByteStreamControllerEnqueue(stream.[[controller]], chunk).
+  ReadableByteStreamControllerEnqueue(aCx, controller, chunk, aRv);
+}
+
+// https://streams.spec.whatwg.org/#readablestream-current-byob-request-view
+void ReadableStream::GetCurrentBYOBRequestView(
+    JSContext* aCx, JS::MutableHandle<JSObject*> aView, ErrorResult& aRv) {
+  aView.set(nullptr);
+
+  // Step 1: Assert: stream.[[controller]] implements
+  // ReadableByteStreamController.
+  MOZ_ASSERT(mController->IsByte());
+
+  // Step 2: Let byobRequest be !
+  // ReadableByteStreamControllerGetBYOBRequest(stream.[[controller]]).
+  RefPtr<ReadableStreamBYOBRequest> byobRequest =
+      mController->AsByte()->GetByobRequest(aCx, aRv);
+
+  // Step 3: If byobRequest is null, then return null.
+  if (!byobRequest || aRv.Failed()) {
+    return;
+  }
+
+  // Step 4: Return byobRequest.[[view]].
+  byobRequest->GetView(aCx, aView);
+}
+
+// https://streams.spec.whatwg.org/#readablestream-get-a-reader
+// To get a reader for a ReadableStream stream, return ?
+// AcquireReadableStreamDefaultReader(stream). The result will be a
+// ReadableStreamDefaultReader.
+already_AddRefed<mozilla::dom::ReadableStreamDefaultReader>
+ReadableStream::GetReader(ErrorResult& aRv) {
+  return AcquireReadableStreamDefaultReader(this, aRv);
+}
+
+}  // namespace mozilla::dom