Add methods for creating V8 extras-based ReadableStreams from C++

Source/core/testing/v8/WebCoreTestSupport.cpp

Index: Source/core/testing/v8/WebCoreTestSupport.cpp
diff --git a/Source/core/testing/v8/WebCoreTestSupport.cpp b/Source/core/testing/v8/WebCoreTestSupport.cpp
index f17e86d85085a312ddf76f4da376840662068cf3..dd8ea4716fc59172b4780c5e0d645faed141741e 100644
--- a/Source/core/testing/v8/WebCoreTestSupport.cpp
+++ b/Source/core/testing/v8/WebCoreTestSupport.cpp
@@ -44,7 +44,7 @@ void injectInternalsObject(v8::Local<v8::Context> context)
     v8::Local<v8::Object> global = scriptState->context()->Global();
     ExecutionContext* executionContext = scriptState->executionContext();
     if (executionContext->isDocument()) {
-        v8::Local<v8::Value> internals = toV8(Internals::create(toDocument(executionContext)), global, scriptState->isolate());
+        v8::Local<v8::Value> internals = toV8(Internals::create(scriptState), global, scriptState->isolate());
         ASSERT(!internals.IsEmpty());
         v8CallOrCrash(global->Set(scriptState->context(), v8AtomicString(scriptState->isolate(), Internals::internalsId), internals));
     }