Set V8 extras mode in gin::V8Initializer.

third_party/WebKit/Source/bindings/core/v8/V8Initializer.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 367 matching lines @@
 void V8Initializer::initializeMainThreadIfNeeded()
 {
     ASSERT(isMainThread());
 
     static bool initialized = false;
     if (initialized)
         return;
     initialized = true;
 
     DEFINE_STATIC_LOCAL(ArrayBufferAllocator, arrayBufferAllocator, ());
-    gin::IsolateHolder::Initialize(gin::IsolateHolder::kNonStrictMode, &arrayBufferAllocator);
+    auto v8ExtrasMode = RuntimeEnabledFeatures::experimentalV8ExtrasEnabled() ? gin::IsolateHolder::kExperimentalV8Extras : gin::IsolateHolder::kStableV8Extras;
+    gin::IsolateHolder::Initialize(gin::IsolateHolder::kNonStrictMode, v8ExtrasMode, &arrayBufferAllocator);
 
     v8::Isolate* isolate = V8PerIsolateData::initialize();
 
     initializeV8Common(isolate);
 
     v8::V8::SetFatalErrorHandler(reportFatalErrorInMainThread);
     v8::V8::AddMessageListener(messageHandlerInMainThread);
     v8::V8::SetFailedAccessCheckCallbackFunction(failedAccessCheckCallbackInMainThread);
     v8::V8::SetAllowCodeGenerationFromStringsCallback(codeGenerationCheckCallbackInMainThread);
 
@@ skipping 64 matching lines @@
 
     v8::V8::AddMessageListener(messageHandlerInWorker);
     v8::V8::SetFatalErrorHandler(reportFatalErrorInWorker);
 
     uint32_t here;
     isolate->SetStackLimit(reinterpret_cast<uintptr_t>(&here - kWorkerMaxStackSize / sizeof(uint32_t*)));
     isolate->SetPromiseRejectCallback(promiseRejectHandlerInWorker);
 }
 
 } // namespace blink