ignore failure -- pdf gradients on mac-mini

expectations/gm/Test-Mac10.8-MacMini4.1-GeForce320M-x86_64-Release/expected-results.json

 {
   "actual-results": {
     "failed": null, 
     "failure-ignored": null, 
     "no-comparison": null, 
     "succeeded": null
   }, 
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": [
@@ skipping 3972 matching lines @@
           "bitmap-64bitMD5", 
           6723721717118023218
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "c_gms_pdf-native.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
-          5474649563443617731
+          1769720779591099491
         ]
       ], 
+      "ignore-failure": true, 
       "reviewed-by-human": true
     }, 
     "canvas-layer-state_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           12670698167582780333
         ]
       ], 
       "reviewed-by-human": true
@@ skipping 15959 matching lines @@
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           11835374726311942978
         ]
       ], 
       "reviewed-by-human": true
     }
   }
 }