Revert of Revert "De-virtualize SkCanvas save/restore."

Revert of Revert "De-virtualize SkCanvas save/restore." (https://codereview.chromium.org/194923008/)

Reason for revert:
Re-landing after roll fix.

Original issue's description:
> Revert "De-virtualize SkCanvas save/restore."
> 
> (To allow a roll fix into the tree).
> 
> This reverts commit edf702204be42c945254191f9f9cd6585b3d189b.
> 
> R=halcanary@google.com
> 
> Committed: https://code.google.com/p/skia/source/detail?r=13748

TBR=halcanary@google.com,fmalita@chromium.org
NOTREECHECKS=true
NOTRY=true

Committed: http://code.google.com/p/skia/source/detail?r=13754

[fmalita_google_do_not_use, 2014-03-11 23:46:57]

Created Revert of Revert "De-virtualize SkCanvas save/restore."

[commit-bot: I haz the power, 2014-03-11 23:47:03]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/fmalita@google.com/196323003/1

[commit-bot: I haz the power, 2014-03-11 23:47:51]

Change committed as 13754

[fmalita_google_do_not_use, 2014-03-12 15:07:56]

A revert of this CL has been created in
https://codereview.chromium.org/197553002/ by fmalita@google.com.

The reason for reverting is: Pulling out to rename the virtuals..