New GM for testing circle blur optimization

gyp/gmslides.gypi

 # include this gypi to include all the golden master slides.
 {
   'include_dirs': [
     '../gm',
     # include dirs needed by particular GMs
     '../src/utils/debugger',
     '../src/images',
     '../src/lazy',
   ],
   'sources': [
@@ skipping 14 matching lines @@
     '../gm/bitmapcopy.cpp',
     '../gm/bitmapmatrix.cpp',
     '../gm/bitmapfilters.cpp',
     '../gm/bitmappremul.cpp',
     '../gm/bitmaprect.cpp',
     '../gm/bitmaprecttest.cpp',
     '../gm/bitmapscroll.cpp',
     '../gm/bitmapshader.cpp',
     '../gm/bitmapsource.cpp',
     '../gm/bleed.cpp',
+    '../gm/blurcircles.cpp',
     '../gm/blurs.cpp',
     '../gm/blurquickreject.cpp',
     '../gm/blurrect.cpp',
     '../gm/blurroundrect.cpp',
     '../gm/canvasstate.cpp',
     '../gm/circles.cpp',
     '../gm/circularclips.cpp',
     '../gm/clippedbitmapshaders.cpp',
     '../gm/coloremoji.cpp',
     '../gm/colorfilterimagefilter.cpp',
@@ skipping 177 matching lines @@
         # fulfilling. See http://skbug.com/1978
         '../gm/verylargebitmap.cpp',
       ],
 
       'sources': [
         '../gm/androidfallback.cpp',
       ],
     }],
   ],
 }