Remove the obsolete OverwriteMode optimization.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index c64f006c27c5e769f7e35dc161b9b6f2ec82c27d..590dbbb027c789670cd565f13f58d0de6e4fd3eb 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -90,9 +90,8 @@ Callable CodeFactory::CompareIC(Isolate* isolate, Token::Value op) {
 
 
 // static
-Callable CodeFactory::BinaryOpIC(Isolate* isolate, Token::Value op,
-                                 OverwriteMode mode) {
-  BinaryOpICStub stub(isolate, op, mode);
+Callable CodeFactory::BinaryOpIC(Isolate* isolate, Token::Value op) {
+  BinaryOpICStub stub(isolate, op);
   return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
 }