Fix assertion failure in RespondInternal after transferring array buffer in RespondWithNewView

Store view byte length before transferring.

Author: nidhijaju

index.bs

@@ -3489,9 +3489,10 @@ The following abstract operations support the implementation of the
     |view|.\[[ViewedArrayBuffer]].\[[ByteLength]], throw a {{RangeError}} exception.
  1. If |firstDescriptor|'s [=pull-into descriptor/bytes filled=] + |view|.\[[ByteLength]] >
     |firstDescriptor|'s [=pull-into descriptor/byte length=], throw a {{RangeError}} exception.
+ 1. Let |viewByteLength| be |view|.\[[ByteLength]].
  1. Set |firstDescriptor|'s [=pull-into descriptor/buffer=] to ?
     [$TransferArrayBuffer$](|view|.\[[ViewedArrayBuffer]]).
- 1. Perform ? [$ReadableByteStreamControllerRespondInternal$](|controller|, |view|.\[[ByteLength]]).
+ 1. Perform ? [$ReadableByteStreamControllerRespondInternal$](|controller|, |viewByteLength|).
 </div>
 
 <div algorithm>

reference-implementation/lib/abstract-ops/readable-streams.js

@@ -1634,9 +1634,11 @@ function ReadableByteStreamControllerRespondWithNewView(controller, view) {
     throw new RangeError('The region specified by view is larger than byobRequest');
   }
 
+  const viewByteLength = view.byteLength;
+
   firstDescriptor.buffer = TransferArrayBuffer(view.buffer);
 
-  ReadableByteStreamControllerRespondInternal(controller, view.byteLength);
+  ReadableByteStreamControllerRespondInternal(controller, viewByteLength);
 }
 
 function ReadableByteStreamControllerShiftPendingPullInto(controller) {