Use the blink main thread isolate for v8 unit tests.

chrome/test/base/v8_unit_test.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_TEST_BASE_V8_UNIT_TEST_H_
 #define CHROME_TEST_BASE_V8_UNIT_TEST_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 50 matching lines @@
   // will log |args| to the console and also signal an error condition causing
   // |RunJavascriptF| to fail.
   static void Error(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   // This method is bound to a method "chrome.send" in the context. When
   // test_api calls testDone with |args| to report its results, this will
   // capture and hold the results for analysis by |RunJavascriptF|.
   static void ChromeSend(const v8::FunctionCallbackInfo<v8::Value>& args);
 
  private:
-  // A helper class to ensure that the lifetimes of the Isolate and the
-  // HandleScope are correctly nested.
-  class IsolateScope {
-   public:
-    IsolateScope() : isolate_(v8::Isolate::New()) { isolate_->Enter(); }
-
-    ~IsolateScope() {
-      isolate_->Exit();
-      isolate_->Dispose();
-    }
-
-    v8::Isolate* isolate() const { return isolate_; }
-
-   private:
-    v8::Isolate* isolate_;
-
-    DISALLOW_COPY_AND_ASSIGN(IsolateScope);
-  };
-
-  // A handy shortcut.
-  v8::Isolate* isolate() const { return isolate_scope_.isolate(); }
-
   // Executes all added javascript libraries. Returns true if no errors.
   bool ExecuteJavascriptLibraries();
 
   // Initializes paths and libraries.
   void InitPathsAndLibraries();
 
-  IsolateScope isolate_scope_;
-
   // Handle scope that is used throughout the life of this class.
   v8::HandleScope handle_scope_;
 
   // Context for the JavaScript in the test.
   v8::Persistent<v8::Context> context_;
 
   // User added libraries.
   std::vector<base::FilePath> user_libraries_;
 };
 
 #endif  // CHROME_TEST_BASE_V8_UNIT_TEST_H_