Make maps in monomorphic IC stubs weak.

src/lithium-codegen.cc

 // Copyright 2013 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
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@@ skipping 193 matching lines @@
     code->constant_pool()->set_weak_object_state(
         ConstantPoolArray::WEAK_OBJECTS_IN_OPTIMIZED_CODE);
   }
 #ifdef VERIFY_HEAP
   // This disables verification of weak embedded objects after full GC.
   // AddDependentCode can cause a GC, which would observe the state where
   // this code is not yet in the depended code lists of the embedded maps.
   NoWeakObjectVerificationScope disable_verification_of_embedded_objects;
 #endif
   for (int i = 0; i < maps.length(); i++) {
-    maps.at(i)->AddDependentCode(DependentCode::kWeaklyEmbeddedGroup, code);
+    maps.at(i)->AddDependentCode(DependentCode::kWeakCodeGroup, code);
   }
   for (int i = 0; i < objects.length(); i++) {
     AddWeakObjectToCodeDependency(isolate()->heap(), objects.at(i), code);
   }
   for (int i = 0; i < cells.length(); i++) {
     AddWeakObjectToCodeDependency(isolate()->heap(), cells.at(i), code);
   }
 }
 
 
 } }  // namespace v8::internal