Remove the LookupResult IsValid method because it is confusing....

src/stub-cache.cc

 // Copyright 2006-2009 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 1052 matching lines @@
 }
 
 
 Object* StubCompiler::GetCodeWithFlags(Code::Flags flags, String* name) {
   if (FLAG_print_code_stubs && (name != NULL)) {
     return GetCodeWithFlags(flags, *name->ToCString());
   }
   return GetCodeWithFlags(flags, reinterpret_cast<char*>(NULL));
 }
 
+
 void StubCompiler::LookupPostInterceptor(JSObject* holder,
                                          String* name,
                                          LookupResult* lookup) {
   holder->LocalLookupRealNamedProperty(name, lookup);
-  if (lookup->IsNotFound()) {
+  if (!lookup->IsProperty()) {
+    lookup->NotFound();
     Object* proto = holder->GetPrototype();
     if (proto != Heap::null_value()) {
       proto->Lookup(name, lookup);
     }
   }
 }
 
 
 
 Object* LoadStubCompiler::GetCode(PropertyType type, String* name) {
@@ skipping 36 matching lines @@
   if (!result->IsFailure()) {
     Code* code = Code::cast(result);
     USE(code);
     LOG(CodeCreateEvent(Logger::STUB_TAG, code, "ConstructStub"));
   }
   return result;
 }
 
 
 } }  // namespace v8::internal