Make maps in monomorphic IC stubs weak.

src/handles.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 745 matching lines @@
 #endif
   return deferred;
 }
 
 
 void AddWeakObjectToCodeDependency(Heap* heap,
                                    Handle<Object> object,
                                    Handle<Code> code) {
   heap->EnsureWeakObjectToCodeTable();
   Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(*object));
-  dep = DependentCode::Insert(dep, DependentCode::kWeaklyEmbeddedGroup, code);
+  dep = DependentCode::Insert(dep, DependentCode::kWeakCodeGroup, code);
   CALL_HEAP_FUNCTION_VOID(heap->isolate(),
                           heap->AddWeakObjectToCodeDependency(*object, *dep));
 }
 
 
 } }  // namespace v8::internal