Bug 1593170. Skip 1553571-1.html reftest on android debug webrender. r=mattwoodrow

The changes to make the test harness avoid busy waiting with setTimeout(0)'s made this test fail on Android 8.0 debug webrender. In order to get an active layer the test tweaks a transform slightly that has no visual effect every 74 ms. This is necessary to test the bug as far as I can tell (I wrote the test). The test times out because MakeProgress never makes any progress, there is always an afterpaint pending or an after paint has fired and we need to update the canvas for it. The painting and running through the settimeouts etc of the reftest harness take slightly too long. Before the changes to remove the busy waits we were just barely passing this test, it took 76 seconds in once instance that I checked and hundreds of iterations before we could make progress. Haven't debugged exactly why removing the busywaits makes this fail but it doesn't seem important.

Differential Revision: https://phabricator.services.mozilla.com/D52650

--HG--
extra : moz-landing-system : lando

layout/reftests/bugs/reftest.list

@@ -2076,7 +2076,7 @@ skip-if(!asyncPan) == 1544895.html 1544895-ref.html
 == 1547759-1.html 1547759-1-ref.html
 == 1548809.html 1548809-ref.html
 != 1552789-1.html 1552789-ref-1.html
-pref(image.downscale-during-decode.enabled,true) == 1553571-1.html 1553571-1-ref.html
+pref(image.downscale-during-decode.enabled,true) skip-if(Android&&webrender) == 1553571-1.html 1553571-1-ref.html
 == 1558937-1.html 1558937-1-ref.html
 != 1563484.html 1563484-notref.html
 == 1563484.html 1563484-ref.html