Fix -webkit-cross-fade crash on certain calc() expressions during parsing.
Note that StyleCrossfadeImage::ComputedCSSValue() already has code to
do clamping for values that we could not clamp during parsing.
We need to do the computation of the weights up-front during StyleImage
construction, when we have the length resolver available; we should
probably refer less to the original value, but that's not a cleanup
that we need to do at this stage.
Bug: 40946458
Change-Id: I5680a7a663a57d89d29e448b5edf531b514f787e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6041238
Reviewed-by: Rune Lillesveen futhark@chromium.org
Commit-Queue: Steinar H Gunderson sesse@chromium.org
Cr-Commit-Position: refs/heads/main@{#1387559}