[Animation Worklet] Remove incorrect test expectation for flaky test

Dashboard:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_layout_tests&tests=virtual%2Fthreaded%2Fexternal%2Fwpt%2Fanimation-worklet%2Fworklet-animation-pause-resume.https.html%20

Mark test flaky only on linux to bring test coverage back on mac / win.

TBR=majidvp@chromium.org
NOTRY=true

Bug: 915352
Change-Id: I8ddb92ccecd43b2c4c6588558526f39cc841c4e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1501513
Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637518}
1 file changed