Split out libplatform into a separate libary

include/v8-platform.h

 // Copyright 2013 the V8 project 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 V8_V8_PLATFORM_H_
 #define V8_V8_PLATFORM_H_
 
 #include "v8.h"
 
 namespace v8 {
@@ skipping 19 matching lines @@
   /**
    * This enum is used to indicate whether a task is potentially long running,
    * or causes a long wait. The embedder might want to use this hint to decide
    * whether to execute the task on a dedicated thread.
    */
   enum ExpectedRuntime {
     kShortRunningTask,
     kLongRunningTask
   };
 
+  virtual ~Platform() {}
+
   /**
    * Schedules a task to be invoked on a background thread. |expected_runtime|
    * indicates that the task will run a long time. The Platform implementation
    * takes ownership of |task|. There is no guarantee about order of execution
    * of tasks wrt order of scheduling, nor is there a guarantee about the
    * thread the task will be run on.
    */
   virtual void CallOnBackgroundThread(Task* task,
                                       ExpectedRuntime expected_runtime) = 0;
 
   /**
    * Schedules a task to be invoked on a foreground thread wrt a specific
    * |isolate|. Tasks posted for the same isolate should be execute in order of
    * scheduling. The definition of "foreground" is opaque to V8.
    */
   virtual void CallOnForegroundThread(Isolate* isolate, Task* task) = 0;
-
- protected:
-  virtual ~Platform() {}
 };
 
 }  // namespace v8
 
 #endif  // V8_V8_PLATFORM_H_