Blacklist tiles_rt-gpu gm imagefilterscropped on GalaxyS4

BUG=skia:3802

Review URL: https://codereview.chromium.org/1115303004

tools/dm_flags.py

@@ -134,6 +134,10 @@ def get_args(bot):
     blacklist.extend('gpu image subset _ msaa image subset _'.split(' '))
     blacklist.extend('msaa16 gm _ tilemodesProcess'.split(' '))
 
+  if 'GalaxyS4' in bot:
+    # This occasionally runs forever. skia:3802
+    blacklist.extend('tiles_rt-gpu gm _ imagefilterscropped'.split(' '))
+
   if blacklist:
     args.append('--blacklist')
     args.extend(blacklist)