[stubs] Port KeyedStoreIC_Megamorphic stub to Turbofan

src/ic/keyed-store-generic.h

+// 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.
+
+#ifndef V8_SRC_IC_KEYED_STORE_GENERIC_H_
+#define V8_SRC_IC_KEYED_STORE_GENERIC_H_
+
+#include "src/code-stub-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+class KeyedStoreGenericGenerator {
+ public:
+  static void Generate(CodeStubAssembler* assembler,
+                       const CodeStubAssembler::StoreICParameters* p,
+                       LanguageMode language_mode);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_SRC_IC_KEYED_STORE_GENERIC_H_