[cc/animation] Remove some dead code

Code was found via Chromium coverage report and then some sleuthing to
spot a method that was only called from a test.

Bug: 252472
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I7223c9210d336fbec89b923e903bd95a64865d40
Reviewed-on: https://chromium-review.googlesource.com/1060106
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559193}
10 files changed