add GM to test imagefilters + xfermodes

gyp/gmslides.gypi

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # include this gypi to include all the golden master slides.
 {
   'include_dirs': [
     '../gm',
     # include dirs needed by particular GMs
     '../src/utils/debugger',
@@ skipping 116 matching lines @@
         '../gm/imageblur.cpp',
         '../gm/imageblur2.cpp',
         '../gm/imageblurtiled.cpp',
         '../gm/imagemagnifier.cpp',
         '../gm/imageresizetiled.cpp',
         '../gm/inversepaths.cpp',
         '../gm/lerpmode.cpp',
         '../gm/lighting.cpp',
         '../gm/lumafilter.cpp',
         '../gm/image.cpp',
+        '../gm/imagefilters.cpp',
         '../gm/imagefiltersbase.cpp',
         '../gm/imagefiltersclipped.cpp',
         '../gm/imagefilterscropped.cpp',
         '../gm/imagefilterscropexpand.cpp',
         '../gm/imagefiltersgraph.cpp',
         '../gm/imagefiltersscaled.cpp',
         '../gm/imagefilterstransformed.cpp',
         '../gm/internal_links.cpp',
         '../gm/lcdtext.cpp',
         '../gm/linepaths.cpp',
@@ skipping 126 matching lines @@
         '../gm/shadertext2.cpp',
         '../gm/shadertext3.cpp',
 
         # TODO(reed): Allocates more memory than Android devices are capable of
         # fulfilling. See http://skbug.com/1978
         '../gm/verylargebitmap.cpp',
       ],
     }],
   ],
 }