Don't animate a progress bar if it isn't animated
The paint path for HTML Progress elements only uses animated
values if the element is "indeterminant", having no "value"
attribute. Yet the LayoutProgress code was always setting up and
using an animation timer, and requesting paint invalidation
repeatedly, even if the value never changed.
Re-enables a test on Mac that should now pass.
Adds a unit test to verify the timer starts and stops as required.
R=wangxianzhu@chromium.org
BUG=570756
Review URL: https://codereview.chromium.org/1721943002
Cr-Commit-Position: refs/heads/master@{#377405}
6 files changed
