GitLab

Roll in the most recent version of:
testharness.js, testdriver.js, idlharness.js.

(webidl2.js has not changed in wpt)

Bug: 866467
Change-Id: I5be57429726e2179e0482514158be0e5ec49be04
Reviewed-on: https://chromium-review.googlesource.com/1146804
Commit-Queue: Philip Jägenstedt <foolip@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577252}