Ship CSS Paint API

We already have 3 LGTMs from the API owners:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/Jex3idOld48

This CL removes the experimental flag for this feature.

Bug: 578252
Change-Id: Id745a0d3bc2f7c8a77ba9f7a49b1a67c8456676e
Reviewed-on: https://chromium-review.googlesource.com/862188
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#529585}
2 files changed