Turn on quilt mode in DM.

gm/downsamplebitmap.cpp

Index: gm/downsamplebitmap.cpp
diff --git a/gm/downsamplebitmap.cpp b/gm/downsamplebitmap.cpp
index 4b97804b01f74e70c627f5ecc80319d37a2eb943..00b1a4b5879584405c4efd2e6a553c3059ce05b3 100644
--- a/gm/downsamplebitmap.cpp
+++ b/gm/downsamplebitmap.cpp
@@ -40,6 +40,13 @@ public:
     }
 
 protected:
+    virtual uint32_t onGetFlags() const SK_OVERRIDE {
+        if (SkPaint::kHigh_FilterLevel != fFilterLevel) {
+            return kSkipTiled_Flag;
+        }
+        return 0;
+    }
+
     virtual SkString onShortName() SK_OVERRIDE {
         return fName;
     }