Start using the overwrite mode from the full codegens to generate...

src/full-codegen.h

 // Copyright 2010 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 219 matching lines @@
    private:
     static const int kForInStackElementCount = 5;
     DISALLOW_COPY_AND_ASSIGN(ForIn);
   };
 
   enum Location {
     kAccumulator,
     kStack
   };
 
+  // Compute the frame pointer relative offset for a given local or
+  // parameter slot.
   int SlotOffset(Slot* slot);
 
+  // Determine whether or not to inline the smi case for the given
+  // operation.
+  bool ShouldInlineSmiCase(Token::Value op);
+
   // Emit code to convert a pure value (in a register, slot, as a literal,
   // or on top of the stack) into the result expected according to an
   // expression context.
   void Apply(Expression::Context context, Register reg);
 
   // Slot cannot have type Slot::LOOKUP.
   void Apply(Expression::Context context, Slot* slot);
 
   void Apply(Expression::Context context, Literal* lit);
   void ApplyTOS(Expression::Context context);
@@ skipping 124 matching lines @@
   // Load a value from a named property.
   // The receiver is left on the stack by the IC.
   void EmitNamedPropertyLoad(Property* expr);
 
   // Load a value from a keyed property.
   // The receiver and the key is left on the stack by the IC.
   void EmitKeyedPropertyLoad(Property* expr);
 
   // Apply the compound assignment operator. Expects the left operand on top
   // of the stack and the right one in the accumulator.
-  void EmitBinaryOp(Token::Value op, Expression::Context context);
+  void EmitBinaryOp(Token::Value op,
+                    Expression::Context context,
+                    OverwriteMode mode);
 
   // Assign to the given expression as if via '='. The right-hand-side value
   // is expected in the accumulator.
   void EmitAssignment(Expression* expr);
 
   // Complete a variable assignment.  The right-hand-side value is expected
   // in the accumulator.
   void EmitVariableAssignment(Variable* var,
                               Token::Value op,
                               Expression::Context context);
@@ skipping 74 matching lines @@
 
   friend class NestedStatement;
 
   DISALLOW_COPY_AND_ASSIGN(FullCodeGenerator);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FULL_CODEGEN_H_