Add gpu fast path for two point conical gradients

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 62 matching lines @@
     '../gm/filltypes.cpp',
     '../gm/filltypespersp.cpp',
     '../gm/filterbitmap.cpp',
     '../gm/fontcache.cpp',
     '../gm/fontmgr.cpp',
     '../gm/fontscaler.cpp',
     '../gm/gammatext.cpp',
     '../gm/getpostextpath.cpp',
     '../gm/giantbitmap.cpp',
     '../gm/gradients.cpp',
+    '../gm/gradients_2pt_conical.cpp',
     '../gm/gradients_no_texture.cpp',
     '../gm/gradientDirtyLaundry.cpp',
     '../gm/gradient_matrix.cpp',
     '../gm/gradtext.cpp',
     '../gm/hairlines.cpp',
     '../gm/hairmodes.cpp',
     '../gm/hittestpath.cpp',
     '../gm/imagealphathreshold.cpp',
     '../gm/imageblur.cpp',
     '../gm/imageblurtiled.cpp',
@@ skipping 127 matching lines @@
         # fulfilling. See http://skbug.com/1978
         '../gm/verylargebitmap.cpp',
       ],
 
       'sources': [
         '../gm/androidfallback.cpp',
       ],
     }],
   ],
 }