Ignore the failure of this flaky PDF test.

expectations/gm/Test-Mac10.6-MacMini4.1-GeForce320M-x86-Release/expected-results.json

 {
   "actual-results": {
     "failed": null, 
     "failure-ignored": null, 
     "no-comparison": null, 
     "succeeded": null
   }, 
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": [
@@ skipping 12277 matching lines @@
       "reviewed-by-human": false
     }, 
     "tilemode_gradient_pdf-mac.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           12114185262432977992
         ]
       ], 
       "bugs": [
-        1578
-      ], 
-      "reviewed-by-human": false
+        1100
+      ],
+      "ignore-failure": true
     }, 
     "tilemode_gradient_pdf-poppler.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           9041357500969159453
         ]
       ], 
       "bugs": [
         1578
@@ skipping 647 matching lines @@
           "bitmap-64bitMD5", 
           10424380103329133154
         ]
       ], 
       "bugs": [
         1578
       ], 
       "reviewed-by-human": false
     }
   }
-}
+}