RPC:
* added `@deprecated` statements and additional comments
* removed `this._destroyed` for the listener checks, because the
  listener is removed when called `destroy()`.
* added `this._port.close()` in addition to removing the listner.

`bridge-test`:
* refactor all the `function () {}` to arrow functions

`frame-rpc-test.js`:
* added these tests to check the `MessageChannel` functionality.