Add Maplike<> utility mixin class for implementing maplike interfaces

Source/modules/webmidi/MIDIInputMap.cpp

 // Copyright 2014 The Chromium 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 "config.h"
 #include "modules/webmidi/MIDIInputMap.h"
 
-#include "bindings/core/v8/ScriptState.h"
 #include "bindings/modules/v8/V8MIDIInput.h"
 
 namespace blink {
 
 MIDIInputMap::MIDIInputMap(const HeapHashMap<String, Member<MIDIInput>> map)
     : MIDIPortMap<MIDIInput>(map)
 {
 }
 
-ScriptValue MIDIInputMap::getForBinding(ScriptState* scriptState, const String& id)
-{
-    MIDIInput* result = get(id);
-    if (result)
-        return ScriptValue(scriptState, toV8(result, scriptState->context()->Global(), scriptState->isolate()));
-    return ScriptValue(scriptState, v8::Undefined(scriptState->isolate()));
-}
-
 } // namespace blink