Remove the obsolete OverwriteMode optimization.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 9bf4d8e3efb6c6496507baffe7ea725d9bae1b74..f6a7414fb525af093d8232c35228ce649ec4fa2c 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -2041,19 +2041,15 @@ void FullCodeGenerator::VisitAssignment(Assignment* expr) {
     __ push(r0);  // Left operand goes on the stack.
     VisitForAccumulatorValue(expr->value());
 
-    OverwriteMode mode = expr->value()->ResultOverwriteAllowed()
-        ? OVERWRITE_RIGHT
-        : NO_OVERWRITE;
     SetSourcePosition(expr->position() + 1);
     AccumulatorValueContext context(this);
     if (ShouldInlineSmiCase(op)) {
       EmitInlineSmiBinaryOp(expr->binary_operation(),
                             op,
-                            mode,
                             expr->target(),
                             expr->value());
     } else {
-      EmitBinaryOp(expr->binary_operation(), op, mode);
+      EmitBinaryOp(expr->binary_operation(), op);
     }
 
     // Deoptimization point in case the binary operation may have side effects.
@@ -2444,7 +2440,6 @@ void FullCodeGenerator::EmitKeyedSuperPropertyLoad(Property* prop) {
 
 void FullCodeGenerator::EmitInlineSmiBinaryOp(BinaryOperation* expr,
                                               Token::Value op,
-                                              OverwriteMode mode,
                                               Expression* left_expr,
                                               Expression* right_expr) {
   Label done, smi_case, stub_call;
@@ -2464,7 +2459,7 @@ void FullCodeGenerator::EmitInlineSmiBinaryOp(BinaryOperation* expr,
   patch_site.EmitJumpIfSmi(scratch1, &smi_case);
 
   __ bind(&stub_call);
-  Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), op, mode).code();
+  Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), op).code();
   CallIC(code, expr->BinaryOperationFeedbackId());
   patch_site.EmitPatchInfo();
   __ jmp(&done);
@@ -2596,11 +2591,9 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit) {
 }
 
 
-void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr,
-                                     Token::Value op,
-                                     OverwriteMode mode) {
+void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr, Token::Value op) {
   __ pop(r1);
-  Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), op, mode).code();
+  Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), op).code();
   JumpPatchSite patch_site(masm_);    // unbound, signals no inlined smi code.
   CallIC(code, expr->BinaryOperationFeedbackId());
   patch_site.EmitPatchInfo();
@@ -4846,8 +4839,7 @@ void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
   // Record position before stub call.
   SetSourcePosition(expr->position());
 
-  Handle<Code> code =
-      CodeFactory::BinaryOpIC(isolate(), Token::ADD, NO_OVERWRITE).code();
+  Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), Token::ADD).code();
   CallIC(code, expr->CountBinOpFeedbackId());
   patch_site.EmitPatchInfo();
   __ bind(&done);