[cleanup] Drop handwritten KeyedStoreIC code

src/builtins/builtins-handler.cc

 // Copyright 2016 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.
 
 #include "src/builtins/builtins-utils.h"
 #include "src/builtins/builtins.h"
 #include "src/ic/accessor-assembler.h"
 #include "src/ic/handler-compiler.h"
 #include "src/ic/ic.h"
 #include "src/ic/keyed-store-generic.h"
 
 namespace v8 {
 namespace internal {
 
 void Builtins::Generate_KeyedLoadIC_Megamorphic_TF(
     compiler::CodeAssemblerState* state) {
   AccessorAssembler::GenerateKeyedLoadICMegamorphic(state);
 }
 
 void Builtins::Generate_KeyedLoadIC_Miss(MacroAssembler* masm) {
   KeyedLoadIC::GenerateMiss(masm);
 }
 void Builtins::Generate_KeyedLoadIC_Slow(MacroAssembler* masm) {
   KeyedLoadIC::GenerateRuntimeGetProperty(masm);
 }
 
-void Builtins::Generate_KeyedStoreIC_Megamorphic(MacroAssembler* masm) {
-  KeyedStoreIC::GenerateMegamorphic(masm, SLOPPY);
-}
-
-void Builtins::Generate_KeyedStoreIC_Megamorphic_Strict(MacroAssembler* masm) {
-  KeyedStoreIC::GenerateMegamorphic(masm, STRICT);
-}
-
 void Builtins::Generate_KeyedStoreIC_Megamorphic_TF(
     compiler::CodeAssemblerState* state) {
   KeyedStoreGenericGenerator::Generate(state, SLOPPY);
 }
 
 void Builtins::Generate_KeyedStoreIC_Megamorphic_Strict_TF(
     compiler::CodeAssemblerState* state) {
   KeyedStoreGenericGenerator::Generate(state, STRICT);
 }
 
@@ skipping 114 matching lines @@
   Generate_StoreIC_Slow(state, SLOPPY);
 }
 
 void Builtins::Generate_StoreIC_SlowStrict(
     compiler::CodeAssemblerState* state) {
   Generate_StoreIC_Slow(state, STRICT);
 }
 
 }  // namespace internal
 }  // namespace v8