[bootstrapper] add checks for variable bindings in native scripts.

src/bootstrapper.cc

 // Copyright 2014 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.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 3131 matching lines @@
     Handle<JSFunction> empty_function = CreateEmptyFunction(isolate);
     CreateStrictModeFunctionMaps(empty_function);
     CreateStrongModeFunctionMaps(empty_function);
     CreateIteratorMaps();
     Handle<JSGlobalObject> global_object =
         CreateNewGlobals(global_proxy_template, global_proxy);
     HookUpGlobalProxy(global_object, global_proxy);
     InitializeGlobal(global_object, empty_function, context_type);
     InitializeNormalizedMapCaches();
 
-    // TODO(yangguo): Find a way to prevent accidentially installing properties
-    // on the global object.
     if (!InstallNatives(context_type)) return;
 
     MakeFunctionInstancePrototypeWritable();
 
     if (context_type != THIN_CONTEXT) {
       if (!InstallExtraNatives()) return;
       if (!ConfigureGlobalObjects(global_proxy_template)) return;
     }
     isolate->counters()->contexts_created_from_scratch()->Increment();
     // Re-initialize the counter because it got incremented during snapshot
@@ skipping 56 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8