Revert of Web Animations: Remove dependency on legacy comparison functions (https://codereview.chromium.org/146003004/)

Reason for revert:
Regresses recalc performance in the case of transition all.

Original issue's description:
> Web Animations: Remove dependency on legacy comparison functions
> 
> As this has a potential to impact performance when evaluating transition
> conditions, this patch is being landed in advance of the full removal so that
> we can evaluate results on the perf bots.
> 
> BUG=334225
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=165716

TBR=timloh@chromium.org
BUG=334225

Review URL: https://codereview.chromium.org/147793003

git-svn-id: svn://svn.chromium.org/blink/trunk@166222 bbb929c8-8fbe-4397-9dbb-9b2b20218538