Falling down to unaccelerated when the pattern is accelerated

Adding a function to detect when a renderingcontext2d has pattern and if
it is accelerated. Using that to handle the case when the pattern is big
and unaccelerated and it is being copied to an accelerated canvas.
Falling down to unaccelerated.

Bug: 969713
Change-Id: I32fa5170e9a45528bfe1233317f252d396e733b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1671387
Commit-Queue: Juanmi Huertas <juanmihd@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672255}
6 files changed