This cl moves color and coverage off of drawstate.  In an effort to keep this CL manageable, I have left the compute invariant input / output in a bit of a strange state(fixing this will be complicated).

In addition, NVPR makes this very complicated, and I haven't quite figured out a good way to handle it, so for now color and coverage DO live on optstate, but I will figure out some way to refactor that in future CLs.

BUG=skia:

Review URL: https://codereview.chromium.org/783763002
diff --git a/src/gpu/GrBitmapTextContext.h b/src/gpu/GrBitmapTextContext.h
index 747facf..9aa5dbd 100644
--- a/src/gpu/GrBitmapTextContext.h
+++ b/src/gpu/GrBitmapTextContext.h
@@ -31,7 +31,8 @@
     SkRect                            fVertexBounds;
     GrTexture*                        fCurrTexture;
     GrMaskFormat                      fCurrMaskFormat;
-    SkAutoTUnref<GrGeometryProcessor> fCachedGeometryProcessor;
+    SkAutoTUnref<const GrGeometryProcessor> fCachedGeometryProcessor;
+    SkAutoTUnref<const GrFragmentProcessor> fCachedTextureProcessor;
     // Used to check whether fCachedEffect is still valid.
     uint32_t                          fEffectTextureUniqueID;