Add unit test for r11818.

src/runtime.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 1299 matching lines @@
 
     if (is_var || is_const) {
       // Lookup the property in the global object, and don't set the
       // value of the variable if the property is already there.
       // Do the lookup locally only, see ES5 erratum.
       LookupResult lookup(isolate);
       if (FLAG_es52_globals) {
         Object* obj = *global;
         do {
           JSObject::cast(obj)->LocalLookup(*name, &lookup);
+          if (lookup.IsProperty()) break;
           obj = obj->GetPrototype();
-        } while (!lookup.IsFound() && obj->IsJSObject() &&
+        } while (obj->IsJSObject() &&
                  JSObject::cast(obj)->map()->is_hidden_prototype());
       } else {
         global->Lookup(*name, &lookup);
       }
       if (lookup.IsProperty()) {
         // We found an existing property. Unless it was an interceptor
         // that claims the property is absent, skip this declaration.
         if (lookup.type() != INTERCEPTOR) continue;
         PropertyAttributes attributes = global->GetPropertyAttribute(*name);
         if (attributes != ABSENT) continue;
@@ skipping 12314 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal