Allow SetHiddenValue to accept empty value.

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 2063 matching lines @@
   // slow case.
   CHECK(obj->Set(prop_name, v8::Integer::New(2008)));
   CHECK_EQ(2002, obj->GetHiddenValue(key)->Int32Value());
   CHECK_EQ(2008, obj->Get(prop_name)->Int32Value());
   CHECK_EQ(2002, obj->GetHiddenValue(key)->Int32Value());
   CHECK(obj->Delete(prop_name));
   CHECK_EQ(2002, obj->GetHiddenValue(key)->Int32Value());
 
   HEAP->CollectAllGarbage(i::Heap::kNoGCFlags);
 
+  CHECK(obj->SetHiddenValue(key, Handle<Value>()));
+  CHECK(obj->GetHiddenValue(key).IsEmpty());
+
+  CHECK(obj->SetHiddenValue(key, v8::Integer::New(2002)));
   CHECK(obj->DeleteHiddenValue(key));
   CHECK(obj->GetHiddenValue(key).IsEmpty());
 }
 
 
 THREADED_TEST(Regress97784) {
   // Regression test for crbug.com/97784
   // Messing with the Object.prototype should not have effect on
   // hidden properties.
   v8::HandleScope scope;
@@ skipping 14959 matching lines @@
   v8::HandleScope scope;
   LocalContext context;
 
   // Compile a try-finally clause where the finally block causes a GC
   // while there still is a message pending for external reporting.
   TryCatch try_catch;
   try_catch.SetVerbose(true);
   CompileRun("try { throw new Error(); } finally { gc(); }");
   CHECK(try_catch.HasCaught());
 }