[CompositeAfterPaint] Fix animation test crashes

The tests crashed because the animating element didn't have a layout
object. This is a valid situation in pre-CompositeAfterPaint. We
should just return an animation failure in the case.

Bug: 962191
Change-Id: Ib624a98bde78fbf0e634e61a84201a75ca0bcaa2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1684557
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#674101}
2 files changed