Bugfix: HCheckInstanceType::GetCheckMaskAndTag used an incorrect mask.

src/hydrogen-instructions.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 1515 matching lines @@
 
 
 void HCheckInstanceType::GetCheckMaskAndTag(uint8_t* mask, uint8_t* tag) {
   ASSERT(!is_interval_check());
   switch (check_) {
     case IS_STRING:
       *mask = kIsNotStringMask;
       *tag = kStringTag;
       return;
     case IS_INTERNALIZED_STRING:
-      *mask = kIsNotInternalizedMask;
+      *mask = kIsNotStringMask | kIsNotInternalizedMask;
       *tag = kInternalizedTag;
       return;
     default:
       UNREACHABLE();
   }
 }
 
 
 void HCheckMaps::HandleSideEffectDominator(GVNFlag side_effect,
                                            HValue* dominator) {
@@ skipping 2874 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal