Revert of Initial picture shader implementation

Revert of Initial picture shader implementation (https://codereview.chromium.org/221923007/)

Reason for revert:
breaking the buildbots. Subsequent CL only addressed CompareGMs but GenerateGMs are also failing.

Original issue's description:
> Initial picture shader implementation
> 
> This CL adds an SkPictureShader class to support SkPicture-based
> patterns.
> 
> The implementation renders the picture into an SkBitmap tile and then
> delegates to SkBitmapProcShader for the actual operation.
> 
> R=reed@google.com,robertphillips@google.com,bsalomon@google.com
> 
> Committed: http://code.google.com/p/skia/source/detail?r=14085

TBR=bsalomon@google.com,reed@google.com,robertphillips@google.com,fmalita@chromium.org
NOTREECHECKS=true
NOTRY=true

Committed: http://code.google.com/p/skia/source/detail?r=14087

[benchen, 2014-04-07 23:45:09]

Created Revert of Initial picture shader implementation

[commit-bot: I haz the power, 2014-04-07 23:45:22]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/bensong@google.com/227553010/1

[commit-bot: I haz the power, 2014-04-07 23:46:01]

Change committed as 14087