Bug 1526520 [wpt PR 15190] - Update wpt metadata, a=testonly

wpt-pr: 15190 wpt-type: metadata
2019-02-11 14:15:26 +00:00 · 2019-02-11 14:15:26 +00:00 · 212190d859
--- a/testing/web-platform/meta/animation-worklet/worklet-animation-with-fill-mode.https.html.ini
+++ b/testing/web-platform/meta/animation-worklet/worklet-animation-with-fill-mode.https.html.ini
@ -1,4 +1,5 @@
 [worklet-animation-with-fill-mode.https.html]
+  expected: ERROR
  [Effect with fill mode forwards in after phase produces output that is equivalent to effect's end value.]
    expected: FAIL