Zap map value in the stub-cache on clear.

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 1016 matching lines @@
   FillCache(isolate_, code);
   return code;
 }
 #endif
 
 
 void StubCache::Clear() {
   Code* empty = isolate_->builtins()->builtin(Builtins::kIllegal);
   for (int i = 0; i < kPrimaryTableSize; i++) {
     primary_[i].key = heap()->empty_string();
+    primary_[i].map = NULL;
     primary_[i].value = empty;
   }
   for (int j = 0; j < kSecondaryTableSize; j++) {
     secondary_[j].key = heap()->empty_string();
+    secondary_[j].map = NULL;
     secondary_[j].value = empty;
   }
 }
 
 
 void StubCache::CollectMatchingMaps(SmallMapList* types,
                                     Handle<Name> name,
                                     Code::Flags flags,
                                     Handle<Context> native_context,
                                     Zone* zone) {
@@ skipping 1049 matching lines @@
           Handle<FunctionTemplateInfo>(
               FunctionTemplateInfo::cast(signature->receiver()));
     }
   }
 
   is_simple_api_call_ = true;
 }
 
 
 } }  // namespace v8::internal