Pass the GrCustomStage and key to GrGLProgramStage emitCode.

The key computation may encode some analysis that emitCode may be able to skip by examining the key.
Review URL: https://codereview.appspot.com/6709075

git-svn-id: http://skia.googlecode.com/svn/trunk@6075 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed