Revert 169949 "Oilpan: Move CSSAnimations and CSSAnimationUpdate..."

It broke a bunch of tests in oilpan bots:
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac%20Oilpan/builds/2500

> Oilpan: Move CSSAnimations and CSSAnimationUpdate to oilpan's heap
> 
> BUG=341032
> 
> Review URL: https://codereview.chromium.org/211113002

TBR=haraken@chromium.org

Review URL: https://codereview.chromium.org/199663007

git-svn-id: svn://svn.chromium.org/blink/trunk@170004 bbb929c8-8fbe-4397-9dbb-9b2b20218538