Always fail when trying to store to an undeclared global variable, even if it was found.

src/stub-cache.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 1053 matching lines @@
   return isolate->heap()->no_interceptor_result_sentinel();
 }
 
 
 static MaybeObject* ThrowReferenceError(String* name) {
   // If the load is non-contextual, just return the undefined result.
   // Note that both keyed and non-keyed loads may end up here, so we
   // can't use either LoadIC or KeyedLoadIC constructors.
   IC ic(IC::NO_EXTRA_FRAME, Isolate::Current());
   ASSERT(ic.target()->is_load_stub() || ic.target()->is_keyed_load_stub());
-  if (!ic.SlowIsContextual()) return HEAP->undefined_value();
+  if (!ic.SlowIsUndeclaredGlobal()) return HEAP->undefined_value();
 
   // Throw a reference error.
   HandleScope scope;
   Handle<String> name_handle(name);
   Handle<Object> error =
       FACTORY->NewReferenceError("not_defined",
                                   HandleVector(&name_handle, 1));
   return Isolate::Current()->Throw(*error);
 }
 
@@ skipping 558 matching lines @@
           Handle<FunctionTemplateInfo>(
               FunctionTemplateInfo::cast(signature->receiver()));
     }
   }
 
   is_simple_api_call_ = true;
 }
 
 
 } }  // namespace v8::internal