Revert of Extract most of the mutable state of SkShader into a separate Context objec...

Revert of Extract most of the mutable state of SkShader into a separate Context object. (https://codereview.chromium.org/207683004/)

Reason for revert:
Causing memory leaks in Chromium.

Original issue's description:
> Extract most of the mutable state of SkShader into a separate Context object.
>
> SkShader currently stores some state during draw calls via setContext(...).
> Move that mutable state into a separate SkShader::Context class that is
> constructed on demand for the duration of the draw.
>
> Calls to setContext() are replaced with createContext() which returns a context
> corresponding to the shader object or NULL if the parameters to createContext
> are invalid.
>
> TEST=out/Debug/dm
> BUG=skia:1976
>
> Committed: http://code.google.com/p/skia/source/detail?r=14216

R=scroggo@google.com, skyostil@chromium.org, tomhudson@chromium.org, senorblanco@chromium.org, reed@google.com, dominikg@chromium.org
TBR=dominikg@chromium.org, reed@google.com, scroggo@google.com, senorblanco@chromium.org, skyostil@chromium.org, tomhudson@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=skia:1976

Author: bungeman@google.com

Review URL: https://codereview.chromium.org/241283003

git-svn-id: http://skia.googlecode.com/svn/trunk@14247 2bbb7eff-a529-9590-31e7-b0007b416f81