Reland "[BlinkGenPropertyTrees] Associate each cc::KeyframeModel with ElementId"

This relands the commit 4391edc08203d66f87950a080cbfbfcb2f2b9d22 from
https://chromium-review.googlesource.com/c/chromium/src/+/1297305

The only difference is that the composited-filter-animation test has been made
asynchronous and to wait for the actual time when full saturation should be visible.

TBR=pdr@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux-blink-gen-property-trees;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Bug: 896549
Change-Id: Idd597082b7ebd97d277f0e196236a155a4c0351d
Reviewed-on: https://chromium-review.googlesource.com/c/1347784
Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Robert Flack <flackr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610494}
33 files changed