Revert of Oilpan: Remove all the RefPtrs and most of the raw pointers to style (https://codereview.chromium.org/199013003/)

Reason for revert:
Failures on all oilpan bots.

Example:

http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Oilpan/builds/2296/steps/webkit_tests/logs/stdio

Original issue's description:
> Oilpan: Remove all the RefPtrs and most of the raw pointers to style
> sheets.
> 
> Comment on the cases where the raw pointers cannot be removed at this point.
> 
> Leave the raw pointers in inspector/ alove. They are safe as they are
> now because the inspector leaks all the CSSStyleSheets it is inspecting
> via Persistent handles at this point (and used to leak them all via
> RefPtrs.)
> 
> R=erik.corry@gmail.com, haraken@chromium.org, oilpan-reviews@chromium.org, vegorov@chromium.org
> BUG=
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169250

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

Review URL: https://codereview.chromium.org/196573018

git-svn-id: svn://svn.chromium.org/blink/trunk@169256 bbb929c8-8fbe-4397-9dbb-9b2b20218538