Bug 1486949 - Part 6: Fix ReadableStreamDefaultReader::Read to use the constructor realm r=smaug

Other methods probably should do the same, but for now this fulfills the test requirement. The rest is (or should be) tracked by https://bugzilla.mozilla.org/show_bug.cgi?id=1756661.

Differential Revision: https://phabricator.services.mozilla.com/D153977

dom/bindings/Bindings.conf

@@ -717,10 +717,6 @@ DOMInterfaces = {
     'implicitJSContext': ['close'],
 },
 
-'ReadableStreamDefaultReader': {
-    'implicitJSContext': ['read'],
-},
-
 'Request': {
     'implicitJSContext': [ 'arrayBuffer', 'blob', 'formData', 'json', 'text' ],
 },

dom/streams/ReadableStreamDefaultReader.cpp

@@ -5,6 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/ReadableStreamDefaultReader.h"
+#include "mozilla/dom/AutoEntryScript.h"
 #include "mozilla/dom/ReadableStream.h"
 #include "mozilla/dom/RootedDictionary.h"
 #include "js/PropertyAndElement.h"
@@ -238,8 +239,7 @@ void ReadableStreamDefaultReaderRead(JSContext* aCx,
 // Return a raw pointer here to avoid refcounting, but make sure it's safe
 // (the object should be kept alive by the callee).
 // https://streams.spec.whatwg.org/#default-reader-read
-already_AddRefed<Promise> ReadableStreamDefaultReader::Read(JSContext* aCx,
-                                                            ErrorResult& aRv) {
+already_AddRefed<Promise> ReadableStreamDefaultReader::Read(ErrorResult& aRv) {
   // Step 1.
   if (!mStream) {
     aRv.ThrowTypeError("Reading is not possible after calling releaseLock.");
@@ -253,7 +253,10 @@ already_AddRefed<Promise> ReadableStreamDefaultReader::Read(JSContext* aCx,
   RefPtr<ReadRequest> request = new Read_ReadRequest(promise);
 
   // Step 4.
-  ReadableStreamDefaultReaderRead(aCx, this, request, aRv);
+  AutoEntryScript aes(mGlobal, "ReadableStreamDefaultReader::Read");
+  JSContext* cx = aes.cx();
+
+  ReadableStreamDefaultReaderRead(cx, this, request, aRv);
   if (aRv.Failed()) {
     return nullptr;
   }

dom/streams/ReadableStreamDefaultReader.h

@@ -75,8 +75,7 @@ class ReadableStreamDefaultReader final : public ReadableStreamGenericReader,
   static already_AddRefed<ReadableStreamDefaultReader> Constructor(
       const GlobalObject& aGlobal, ReadableStream& stream, ErrorResult& aRv);
 
-  MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> Read(JSContext* aCx,
-                                                    ErrorResult& aRv);
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> Read(ErrorResult& aRv);
 
   void ReleaseLock(ErrorResult& aRv);
 

testing/web-platform/meta/encoding/streams/realms.window.js.ini

-[realms.window.html]
-  [the output chunks when read is called after write should come from the same realm as the constructor of TextEncoderStream]
-    expected: FAIL
-
-  [the result object when read is called after write should come from the same realm as the constructor of TextDecoderStream]
-    expected: FAIL