Increase error tolerance in animation tests.
They were flaky. Reproducible locally with --iterations=500
fast/animation/request-animation-frame-prefix.html flaked here:
https://ci.chromium.org/ui/p/chromium/builders/try/linux-rel/1872086/test-results
Bug: 351244346
Change-Id: I3e74031c01f7fcc31c23d75722d23d6a05c31688
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5680283
Reviewed-by: Noam Rosenthal nrosenthal@chromium.org
Commit-Queue: Morten Stenshorne mstensho@chromium.org
Cr-Commit-Position: refs/heads/main@{#1324122}