message: License and linting fixes.
diff: -import Promise from "bluebird";
  +/*
  +Copyright 2017 New Vector Ltd
  +
  +Licensed under the Apache License, Version 2.0 (the "License");
  +you may not use this file except in compliance with the License.
  +You may obtain a copy of the License at
  +
  + http://www.apache.org/licenses/LICENSE-2.0
  +Unless required by applicable law or agreed to in writing, software
  +distributed under the License is distributed on an "AS IS" BASIS,
  +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  +See the License for the specific language governing permissions and
  +limitations under the License.
  +*/
  +
  +import Promise from "bluebird";
  function defer() {
  - let resolve, reject;
  + let resolve;
  + let reject;
  let isPending = true;
  - let promise = new Promise(function(...args) {
  + const promise = new Promise(function(...args) {
  resolve = args[0];
  reject = args[1];
  });
  @@ -55,18 +71,18 @@ export default class PostMessageApi {
  if (this._onMsgCallback) {
  return this._onMsgCallback;
  }
  - let self = this;
  + const self = this;
  this._onMsgCallback = function(ev) {
  // THIS IS ALL UNSAFE EXECUTION.
  // We do not verify who the sender of `ev` is!
  - let payload = ev.data;
  + const payload = ev.data;
  // NOTE: Workaround for running in a mobile WebView where a
  // postMessage immediately triggers this callback even though it is
  // not the response.
  if (payload.response === undefined) {
  return;
  }
  - let deferred = self._pending[payload._id];
  + const deferred = self._pending[payload._id];
  if (!deferred) {
  return;
  }
  @@ -83,7 +99,7 @@ export default class PostMessageApi {
  this._counter += 1;
  target = target || "*";
  action._id = Date.now() + "-" + Math.random().toString(36) + "-" + this._counter;
  - let d = defer();
  + const d = defer();
  this._pending[action._id] = d;
  this._window.postMessage(action, target);
  