commit 59f06466fb092c256db7fbe4c392079ddf13e96a
author Stephen McGruer <smcgruer@chromium.org> Wed Mar 21 13:25:28 2018
committer Commit Bot <commit-bot@chromium.org> Wed Mar 21 13:25:28 2018
tree d2fb2d00dff29d05801959e05017fb149bf8531f
parent c5f347933aad5eb5c282b0016aa76569159dbba0

Reland "Web Animations: use WTF::Optional for Animation::start_time_"

This is a reland of c838bf406fc8f97bd8c26a713f80e7290c1f39d3

The original CL contained two subtle bugs from a comparison of
compositor_state_->start_time to start_time_. Previously if both were
'null' (represented by NaN), the comparison would still say they were
inequal because NaN != NaN. The original CL 'fixed' those comparisons,
but it turns out the behavior was intentional. This version of the CL
restores the intentional behavior, adds a test for it, and documents it.

Bug: 791086, 819591
Change-Id: I6587d028e66c6f6a9213b60f8d5f51b1dac3f899
Reviewed-on: https://chromium-review.googlesource.com/956280
Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544679}