Revert of Move all RefPtr's to CSSValue to oilpan transition types, except for the one in CSSCursorImageValue. (https://codereview.chromium.org/184313004/)

Reason for revert:
It seems to break some of our layout tests.

Original issue's description:
> Move all RefPtr's to CSSValue to oilpan transition types, except for the one in CSSCursorImageValue.
> 
> This change gets rid of all but one RefPtr to CSSValue. I have introduced a few persistents core/animation/..., core/css/StylePropertySet, and ElementStyleResources. I plan to attack the one in CSSCursorImageValue subsequently, and then change CSSValue from RefCountedGarbageCollected to GarbageCollectedFinalized.
> 
> R=ager@chromium.org, erik.corry@gmail.com, haraken@chromium.org, oilpan-reviews@chromium.org, tkent@chromium.org, vegorov@chromium.org, zerny@chromium.org
> BUG=341815
> NOTRY=true
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168466

TBR=ager@chromium.org,erik.corry@gmail.com,haraken@chromium.org,oilpan-reviews@chromium.org,tkent@chromium.org,vegorov@chromium.org,zerny@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=341815

Review URL: https://codereview.chromium.org/184853009

git-svn-id: svn://svn.chromium.org/blink/trunk@168492 bbb929c8-8fbe-4397-9dbb-9b2b20218538