[CompositeClipPathAnimation] Fix crash with position: absolute
A new clip path crash was discovered during experimentation,
exacerbated by a recent change that enables clip path animations
when there is a positive delay or clip-path: none.
In this case when the positioning is absolute, the clip path style
property is a nullptr instead of being filled with the value for
none. This breaks assumptiosn in clip path clipper, which assume
(reasonably, based on prior usage of the code) that an element
with a clip path animation or a mask based clip will have a clip path
value in its style.
This change adds conditionals and removes a DCHECK to prevent any
crash in this case.
Bug: 378027650
Change-Id: If7e2814a4de647c1f6cebe6e7f8291419bcac018
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6001026
Reviewed-by: Philip Rogers pdr@chromium.org
Commit-Queue: Claire Chambers clchambers@microsoft.com
Cr-Commit-Position: refs/heads/main@{#1386634}