Remove the obsolete OverwriteMode optimization.

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 230a83da203ea18a61d2e3960a3c1ac1f921602f..3e6ea44ea99a6de8791e5ed8f30eb95ea3751db9 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -1229,10 +1229,9 @@ class CallApiGetterStub : public PlatformCodeStub {
 
 class BinaryOpICStub : public HydrogenCodeStub {
  public:
-  BinaryOpICStub(Isolate* isolate, Token::Value op,
-                 OverwriteMode mode = NO_OVERWRITE)
+  BinaryOpICStub(Isolate* isolate, Token::Value op)
       : HydrogenCodeStub(isolate, UNINITIALIZED) {
-    BinaryOpICState state(isolate, op, mode);
+    BinaryOpICState state(isolate, op);
     set_sub_minor_key(state.GetExtraICState());
   }
 
@@ -1313,10 +1312,8 @@ class BinaryOpICWithAllocationSiteStub FINAL : public PlatformCodeStub {
 
 class BinaryOpWithAllocationSiteStub FINAL : public BinaryOpICStub {
  public:
-  BinaryOpWithAllocationSiteStub(Isolate* isolate,
-                                 Token::Value op,
-                                 OverwriteMode mode)
-      : BinaryOpICStub(isolate, op, mode) {}
+  BinaryOpWithAllocationSiteStub(Isolate* isolate, Token::Value op)
+      : BinaryOpICStub(isolate, op) {}
 
   BinaryOpWithAllocationSiteStub(Isolate* isolate, const BinaryOpICState& state)
       : BinaryOpICStub(isolate, state) {}