Revert of Remove gpu shader optimatization for solid white or trans black colors

Revert of Remove gpu shader optimatization for solid white or trans black colors (https://codereview.chromium.org/375823005/)

Reason for revert:
possible test and gm failures

Original issue's description:
> Remove gpu shader optimatization for solid white or trans black colors
> 
> Running test on the added bench which draws a grid of all white paths, all blue paths, or alternating checkered white/blue paths.
> 
> With optimization in (ms):
>          White       Blue        Checkered
> Linux    ~80         ~80         ~160
> N7       ~800        ~1100       ~1500
> Moto-e   ~830        ~1100       ~2500
> 
> Without optimization in (ms):
>          White       Blue        Checkered
> Linux    ~80         ~80         ~80
> N7       ~1100       ~1100       ~1100
> Moto-e   ~1100       ~1100       ~1500
> 
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/5f78d2251a440443c9eaa321dad058d7a32bfef7

TBR=bsalomon@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/c855ca0c9408d2a218655a138fab9cc18a2b3940

[egdaniel, 2014-07-11 16:12:53]

Created Revert of Remove gpu shader optimatization for solid white or trans
black colors

[commit-bot: I haz the power, 2014-07-11 16:13:32]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/egdaniel@google.com/385163004/1

[commit-bot: I haz the power, 2014-07-11 16:13:40]

Change committed as c855ca0c9408d2a218655a138fab9cc18a2b3940