Fix color emoji.

Removes the GrMaskFormat and single atlas in GrTextStrike.
Replaces it by storing the GrMaskFormat in each GrGlyph, and
doing a lookup for the correct atlas based on that.

Disables color glyph rendering in GrDistanceFieldTextContext
for now.

BUG=skia:2887

Committed: https://skia.googlesource.com/skia/+/bc92163ddfe957ad6ffbb02ac40e0ba75ff82216

Review URL: https://codereview.chromium.org/636183005
diff --git a/src/gpu/GrBitmapTextContext.h b/src/gpu/GrBitmapTextContext.h
index 4bff399..a9805cb 100644
--- a/src/gpu/GrBitmapTextContext.h
+++ b/src/gpu/GrBitmapTextContext.h
@@ -40,13 +40,14 @@
 
     GrTextStrike*                     fStrike;
     void*                             fVertices;
-    int32_t                           fMaxVertices;
+    int                               fCurrVertex;
+    int                               fMaxVertices;
+    SkRect                            fVertexBounds;
     GrTexture*                        fCurrTexture;
+    GrMaskFormat                      fCurrMaskFormat;
     SkAutoTUnref<GrGeometryProcessor> fCachedGeometryProcessor;
     // Used to check whether fCachedEffect is still valid.
     uint32_t                          fEffectTextureUniqueID;
-    int                               fCurrVertex;
-    SkRect                            fVertexBounds;
 
     void init(const GrPaint&, const SkPaint&);
     void appendGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);