Add color emoji fallback for distance field text.

BUG=skia:3033

Review URL: https://codereview.chromium.org/670533002
diff --git a/src/gpu/GrDistanceFieldTextContext.h b/src/gpu/GrDistanceFieldTextContext.h
index 6fa2d6f..e0ef7e2 100644
--- a/src/gpu/GrDistanceFieldTextContext.h
+++ b/src/gpu/GrDistanceFieldTextContext.h
@@ -58,7 +58,7 @@
                                const SkPoint& offset) SK_OVERRIDE;
 
     void init(const GrPaint&, const SkPaint&);
-    void appendGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);
+    bool appendGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);
     void setupCoverageEffect(const SkColor& filteredColor);
     void flush();                 // automatically called by destructor
     void finish();