Violation reports for 'layout-animations'

This CL adds support for generating violation reports for 'layout-animations'
feature policy. The new implementation triggers a report when:
  1- CSS Parser finds usage of @keyframes for one of the banned styles.
  2- element.animate() changes a banned style.

Bug: 902836,867471
Change-Id: I79900603eb0166514d7986dc189ec914bd95f899
Reviewed-on: https://chromium-review.googlesource.com/c/1324138
Commit-Queue: Ehsan Karamad <ekaramad@chromium.org>
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608984}
14 files changed