Deflake color-mix currentcolor tests
Add an extra rAF() to make sure the tests are painted before the
currentcolor change.
Bug: 354513209
Change-Id: Id856a4c66c1d0aebf17a5578f913d261625fdc50
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5756784
Commit-Queue: Rune Lillesveen futhark@chromium.org
Reviewed-by: Ian Kilpatrick ikilpatrick@chromium.org
Cr-Commit-Position: refs/heads/main@{#1336305}