Revert of Revert of Split out CSSParser public API (patchset #1 id:1 of https://codereview.chromium.org/566703002/)

Reason for revert:
Bring it back since the OilPan builder is not a tree closer.

Original issue's description:
> Revert of Split out CSSParser public API (patchset #3 id:40001 of https://codereview.chromium.org/566483002/)
> 
> Reason for revert:
> Caused compiling errors.
> 
> Original issue's description:
> > Split out CSSParser public API
> > 
> > This patch separates the public API of BisonCSSParser from the hundreds
> > of public methods it exposes. The plan is to build a new parser based on
> > the css-syntax specification, which will eventually complete replace the
> > bison-based parser. The functions in this class will do the run-time
> > switching between the bison parser and the new (unwritten) parser.
> > 
> > For the functions here which are only ever used with a newly instantiated
> > BisonCSSParser, I've moved instantiation to inside the CSSParser so that
> > the functions can be static.
> > 
> > This is an updated version of a patch by eseidel from 8 months ago:
> > https://codereview.chromium.org/112933010/
> > 
> > BUG=330389
> > 
> > Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181825
> 
> TBR=eseidel@chromium.org,esprehn@chromium.org,alancutter@chromium.org,timloh@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=330389
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181837

TBR=eseidel@chromium.org,esprehn@chromium.org,alancutter@chromium.org,timloh@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=330389

Review URL: https://codereview.chromium.org/563893002

git-svn-id: svn://svn.chromium.org/blink/trunk@181849 bbb929c8-8fbe-4397-9dbb-9b2b20218538