Put new global var semantics behind a flag until WebKit tests are cleaned up.

test/cctest/test-api.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 12465 matching lines @@
   calling_context2.Dispose();
   calling_context0.Clear();
   calling_context1.Clear();
   calling_context2.Clear();
 }
 
 
 // Check that a variable declaration with no explicit initialization
 // value does shadow an existing property in the prototype chain.
 THREADED_TEST(InitGlobalVarInProtoChain) {
+  i::FLAG_es52_globals = true;
   v8::HandleScope scope;
   LocalContext context;
   // Introduce a variable in the prototype chain.
   CompileRun("__proto__.x = 42");
   v8::Handle<v8::Value> result = CompileRun("var x = 43; x");
   CHECK(!result->IsUndefined());
   CHECK_EQ(43, result->Int32Value());
 }
 
 
@@ skipping 3944 matching lines @@
 
 
 TEST(SecondaryStubCache) {
   StubCacheHelper(true);
 }
 
 
 TEST(PrimaryStubCache) {
   StubCacheHelper(false);
 }