Make global variable initialization consistent with Firefox and Safari...

test/cctest/test-api.cc

 // Copyright 2007-2008 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 7006 matching lines @@
   calling_context2->Exit();
 
   // Dispose the contexts to allow them to be garbage collected.
   calling_context0.Dispose();
   calling_context1.Dispose();
   calling_context2.Dispose();
   calling_context0.Clear();
   calling_context1.Clear();
   calling_context2.Clear();
 }
+
+
+// Check that a variable declaration with no explicit initialization
+// value does not shadow an existing property in the prototype chain.
+//
+// This is consistent with Firefox and Safari.
+//
+// See http://crbug.com/12548.
+THREADED_TEST(InitGlobalVarInProtoChain) {
+  v8::HandleScope scope;
+  LocalContext context;
+  // Introduce a variable in the prototype chain.
+  CompileRun("__proto__.x = 42");
+  v8::Handle<v8::Value> result = CompileRun("var x; x");
+  CHECK(!result->IsUndefined());
+  CHECK_EQ(42, result->Int32Value());
+}