Remove SlowTests entry for svg/animations/svg-animation-policy-once.html

This test was removed (converted to unit test) in
855446c8.

Tbr: schenney@chromium.org
Bug: 998526
Change-Id: I7e84e675607fccd0d57ee677c4f9f3dec62e309d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2050595Reviewed-by: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#740665}

third_party/blink/web_tests/SlowTests

@@ -541,7 +541,6 @@ crbug.com/874695 storage/websql/transaction-callback-isolated-world.html [ Slow
 crbug.com/874695 storage/websql/transaction-error-callback.html [ Slow ]
 crbug.com/874695 storage/websql/transaction-error-callback-isolated-world.html [ Slow ]
 crbug.com/874695 storage/websql/transaction-success-callback-isolated-world.html [ Slow ]
-crbug.com/874695 svg/animations/svg-animation-policy-once.html [ Slow ]
 crbug.com/874695 virtual/android/fullscreen/full-screen-restrictions.html [ Slow ]
 crbug.com/874695 virtual/android/fullscreen/video-specified-size.html [ Slow ]
 crbug.com/874695 virtual/display-compositor-pixel-dump/fast/canvas/display-compositor-pixel-dump/OffscreenCanvas-opaque-background-compositing.html [ Slow ]