Remove the obsolete OverwriteMode optimization.

src/code-factory.h

 // Copyright 2012 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.
 
 #ifndef V8_CODE_FACTORY_H_
 #define V8_CODE_FACTORY_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
@@ skipping 27 matching lines @@
   static Callable KeyedLoadICInOptimizedCode(Isolate* isolate);
   static Callable CallIC(Isolate* isolate, int argc,
                          CallICState::CallType call_type);
   static Callable CallICInOptimizedCode(Isolate* isolate, int argc,
                                         CallICState::CallType call_type);
   static Callable StoreIC(Isolate* isolate, LanguageMode mode);
   static Callable KeyedStoreIC(Isolate* isolate, LanguageMode mode);
 
   static Callable CompareIC(Isolate* isolate, Token::Value op);
 
-  static Callable BinaryOpIC(Isolate* isolate, Token::Value op,
-                             OverwriteMode mode = NO_OVERWRITE);
+  static Callable BinaryOpIC(Isolate* isolate, Token::Value op);
 
   // Code stubs. Add methods here as needed to reduce dependency on
   // code-stubs.h.
   static Callable ToBoolean(
       Isolate* isolate, ToBooleanStub::ResultMode mode,
       ToBooleanStub::Types types = ToBooleanStub::Types());
 
   static Callable ToNumber(Isolate* isolate);
 
   static Callable StringAdd(Isolate* isolate, StringAddFlags flags,
                             PretenureFlag pretenure_flag);
 
   static Callable AllocateHeapNumber(Isolate* isolate);
 
   static Callable CallFunction(Isolate* isolate, int argc,
                                CallFunctionFlags flags);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODE_FACTORY_H_