Add another fail-ignore for flaky dashing4 gm

expectations/gm/Test-Win7-ShuttleA-HD2000-x86_64-Debug/expected-results.json

 {
   "actual-results": {
     "failed": null, 
     "failure-ignored": null, 
     "no-comparison": null, 
     "succeeded": null
   }, 
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": [
@@ skipping 4509 matching lines @@
           "bitmap-64bitMD5", 
           10873004693785991483
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "dashing4_gpu.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
-          130107792326448839
+          4199059907564224666
         ]
       ], 
+      "bugs": [
+        2667
+      ], 
+      "ignore-failure": true, 
       "reviewed-by-human": true
     }, 
     "dashing_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           2587070015488181148
         ]
       ], 
       "bugs": [
@@ skipping 8117 matching lines @@
           14019814087375927425
         ]
       ], 
       "bugs": [
         1578
       ], 
       "reviewed-by-human": false
     }
   }
 }