[ElementTiming] Fix DCHECK about natural width and height

It is possible to do paint for images which have naturalWidth and
naturalHeight equal to 0. Therefore, the DCHECK is relaxed to allow
for this.

Bug: 953994, 879270
Change-Id: I65b1d9463d61e31775c937fad1e104a19d87f58b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582842
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654062}
2 files changed