Use weak cell to embed map in CompareNil IC.

src/ic/ic-compiler.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/ic/handler-compiler.h"
 #include "src/ic/ic-inl.h"
 #include "src/ic/ic-compiler.h"
 
@@ skipping 226 matching lines @@
                                                    CompareNilICStub* stub) {
   Isolate* isolate = receiver_map->GetIsolate();
   Handle<String> name(isolate->heap()->empty_string());
   if (!receiver_map->is_dictionary_map()) {
     Handle<Code> cached_ic =
         Find(name, receiver_map, Code::COMPARE_NIL_IC, stub->GetExtraICState());
     if (!cached_ic.is_null()) return cached_ic;
   }
 
   Code::FindAndReplacePattern pattern;
-  pattern.Add(isolate->factory()->meta_map(), receiver_map);
+  Handle<WeakCell> cell = Map::WeakCellForMap(receiver_map);
+  pattern.Add(isolate->factory()->meta_map(), cell);
   Handle<Code> ic = stub->GetCodeCopy(pattern);
 
   if (!receiver_map->is_dictionary_map()) {
     Map::UpdateCodeCache(receiver_map, name, ic);
   }
 
   return ic;
 }
 
 
@@ skipping 196 matching lines @@
 
   TailCallBuiltin(masm(), Builtins::kKeyedStoreIC_Miss);
 
   return GetCode(kind(), Code::NORMAL, factory()->empty_string());
 }
 
 
 #undef __
 }
 }  // namespace v8::internal