Sync the MessageChannel and MessagePort interfaces with the spec

This exposes the MessagePort interface to workers.

The MessageChannel constructor was exposed to workers in spec and
implementation in 2009:
https://html5.org/r/3325
https://trac.webkit.org/changeset/45381

The MessagePort interface wasn't made exposed in the spec until 2014:
https://html5.org/r/8425

BUG=460722

Review URL: https://codereview.chromium.org/969643002

git-svn-id: svn://svn.chromium.org/blink/trunk@191172 bbb929c8-8fbe-4397-9dbb-9b2b20218538
6 files changed
tree: 04a9ca43921e3d9420a157da7b2b18ae4693b804
  1. third_party/