GitLab

The Web style guide's JS section should link to the ES supported
features doc, and vice versa, so that both are discoverable.

Also gives the ES Support page a proper title:
"ECMAScript Features in Chromium"

Bug: None
Change-Id: I4af3471a4eba1f7377826a35c08cbb8841db411d
Reviewed-on: https://chromium-review.googlesource.com/c/1450586
Commit-Queue: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Auto-Submit: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628553}