Remove obsolete "previous" field from Genesis.

src/bootstrapper.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 131 matching lines @@
 class Genesis BASE_EMBEDDED {
  public:
   Genesis(Isolate* isolate,
           Handle<Object> global_object,
           v8::Handle<v8::ObjectTemplate> global_template,
           v8::ExtensionConfiguration* extensions);
   ~Genesis() { }
 
   Handle<Context> result() { return result_; }
 
-  Genesis* previous() { return previous_; }
-
   Isolate* isolate() const { return isolate_; }
   Factory* factory() const { return isolate_->factory(); }
   Heap* heap() const { return isolate_->heap(); }
 
  private:
   Handle<Context> native_context_;
   Isolate* isolate_;
 
-  // There may be more than one active genesis object: When GC is
-  // triggered during environment creation there may be weak handle
-  // processing callbacks which may create new environments.
-  Genesis* previous_;
-
   Handle<Context> native_context() { return native_context_; }
 
   // Creates some basic objects. Used for creating a context from scratch.
   void CreateRoots();
   // Creates the empty function.  Used for creating a context from scratch.
   Handle<JSFunction> CreateEmptyFunction(Isolate* isolate);
   // Creates the ThrowTypeError function. ECMA 5th Ed. 13.2.3
   Handle<JSFunction> GetThrowTypeErrorFunction();
 
   void CreateStrictModeFunctionMaps(Handle<JSFunction> empty);
@@ skipping 2323 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   ASSERT(!IsActive());
 }
 
 } }  // namespace v8::internal