Add fallback code for TextContexts that don't support all features

src/gpu/GrDistanceFieldTextContext.cpp

Index: src/gpu/GrDistanceFieldTextContext.cpp
diff --git a/src/gpu/GrDistanceFieldTextContext.cpp b/src/gpu/GrDistanceFieldTextContext.cpp
index 505ee39539fa2bc3d746f457d147c2f217bb4619..96cce76d3ba8fede03274e78a71a539a686964df 100755
--- a/src/gpu/GrDistanceFieldTextContext.cpp
+++ b/src/gpu/GrDistanceFieldTextContext.cpp
@@ -13,6 +13,7 @@
 #include "GrIndexBuffer.h"
 #include "GrTextStrike.h"
 #include "GrTextStrike_impl.h"
+#include "SkDraw.h"
 #include "SkGpuDevice.h"
 #include "SkPath.h"
 #include "SkRTConf.h"
@@ -26,6 +27,12 @@ static const int kBaseDFFontSize = 32;
 SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
                 "Dump the contents of the font cache before every purge.");
 
+bool GrDistanceFieldTextContext::CanDraw(const SkPaint& paint, const SkMatrix& ctm) {
+    return !paint.getRasterizer() && !paint.getMaskFilter()
+           && paint.getStyle() == SkPaint::kFill_Style
+           && !SkDraw::ShouldDrawTextAsPaths(paint, ctm);
+}
+
 GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
                                                        const GrPaint& grPaint,
                                                        const SkPaint& skPaint,