Mark convex_poly_clip as flaky on msaa16/win8 bots. Add more tests to ignored_tests.txt after GPU r…

expectations/gm/Test-Win8-ShuttleA-GTX660-x86-Debug/expected-results.json

 {
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           12831071530564277917
         ]
       ], 
       "bugs": [
@@ skipping 6337 matching lines @@
       ], 
       "reviewed-by-human": true
     }, 
     "convex_poly_clip_msaa16.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           8627394447232319577
         ]
       ], 
+      "bugs": [
+        2824
+      ], 
+      "ignore-failure": true, 
       "reviewed-by-human": true
     }, 
     "convex_poly_clip_nvprmsaa4.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           7570814056450667246
         ]
       ], 
       "reviewed-by-human": true
@@ skipping 12960 matching lines @@
           14019814087375927425
         ]
       ], 
       "bugs": [
         1935
       ], 
       "reviewed-by-human": false
     }
   }
 }