Enter V8 context before calling Incoming|OutgoingStream::Reset

As specified in the method comments.

Bug: 1112734
Change-Id: I0e16566014936d396f7f47d27fb0f17cfe2124d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351929Reviewed-by: Adam Rice <ricea@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797550}

third_party/blink/renderer/modules/webtransport/bidirectional_stream.cc

@@ -41,11 +41,13 @@ void BidirectionalStream::OnIncomingStreamClosed(bool fin_received) {
   incoming_stream_->OnIncomingStreamClosed(fin_received);
   // TODO(ricea): Review this behaviour when adding detail to the specification.
   if (!sent_fin_) {
+    ScriptState::Scope scope(outgoing_stream_->GetScriptState());
     outgoing_stream_->Reset();
   }
 }
 
 void BidirectionalStream::Reset() {
+  ScriptState::Scope scope(outgoing_stream_->GetScriptState());
   outgoing_stream_->Reset();
   incoming_stream_->Reset();
 }
@@ -79,6 +81,7 @@ void BidirectionalStream::Trace(Visitor* visitor) const {
 
 void BidirectionalStream::OnIncomingStreamAbort() {
   quic_transport_->ForgetStream(stream_id_);
+  ScriptState::Scope scope(outgoing_stream_->GetScriptState());
   outgoing_stream_->Reset();
 }
 

third_party/blink/renderer/modules/webtransport/outgoing_stream.h

@@ -68,6 +68,8 @@ class MODULES_EXPORT OutgoingStream final
 
   ScriptPromise WritingAborted() const { return writing_aborted_; }
 
+  ScriptState* GetScriptState() { return script_state_; }
+
   void AbortWriting(StreamAbortInfo*);
 
   // Called from QuicTransport via a WebTransportStream. Expects a JavaScript