[Mojo] Move JS bindings out of public

mojo/public/bindings/js/handle.cc

-// Copyright 2013 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 "mojo/public/bindings/js/handle.h"
-
-namespace gin {
-
-v8::Handle<v8::Value> Converter<mojo::Handle>::ToV8(v8::Isolate* isolate,
-                                                    const mojo::Handle& val) {
-  return Converter<MojoHandle>::ToV8(isolate, val.value());
-}
-
-bool Converter<mojo::Handle>::FromV8(v8::Isolate* isolate,
-                                     v8::Handle<v8::Value> val,
-                                     mojo::Handle* out) {
-  return Converter<MojoHandle>::FromV8(isolate, val, out->mutable_value());
-}
-
-}  // namespace gin