Bug 1365177 - Disable w3c-css/submitted/masking/mask-image-1c.html for frequent failures on Windows 10. r=jmaher

--HG--
extra : rebase_source : 006c592b1de230db6dbf12eca4f782e242980726

layout/reftests/w3c-css/submitted/masking/reftest.list

@@ -19,7 +19,7 @@ fuzzy-if(skiaContent,1,30000) fuzzy-if(d2d,1,30000) == mask-mode-to-mask-type.ht
 # mask-image test cases
 == mask-image-1a.html mask-image-1-ref.html
 == mask-image-1b.html mask-image-1-ref.html
-random-if(gtkWidget) == mask-image-1c.html mask-image-1-ref.html # bug 1365177
+random-if(gtkWidget) skip-if(winWidget&&/^Windows\x20NT\x2010\.0/.test(http.oscpu)) == mask-image-1c.html mask-image-1-ref.html # bug 1365177
 == mask-image-1d.html mask-image-1-ref.html
 fuzzy-if(skiaContent||winWidget,1,20000) == mask-image-2.html mask-image-2-ref.html
 == mask-image-3a.html mask-image-3-ref.html