Extensions: Remove old Mojo JS bindings support and AMD-style module support.

This significantly reduces non-Android chrome size. With an official build on Linux,
  before the change - resources.pak 12230694
  after  the change - resources.pak 12069587
The difference is about 160KB.

Bug: 699569, 718047
Change-Id: I2d2f6985cb10c27637a8a7d478001b18ac1b8111
Reviewed-on: https://chromium-review.googlesource.com/804974
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Yuzhu Shen <yzshen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521516}
14 files changed