[CSS] Enable sync of filter-effects WPT

Blink should be running, and contributing to, the filter-effects tests
https://github.com/web-platform-tests/wpt/tree/master/css/filter-effects

The tests currently in css-filter can then easily be moved to
filter-effects.

Change-Id: Ibf50ee79c5456573e76ec42deebdb7bc727612e4
Reviewed-on: https://chromium-review.googlesource.com/c/1325274
Commit-Queue: Philip Jägenstedt <foolip@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606451}

third_party/WebKit/LayoutTests/W3CImportExpectations

@@ -91,7 +91,6 @@ external/wpt/css/css-regions [ Skip ]
 external/wpt/css/css-round-display [ Skip ]
 external/wpt/css/css-ruby [ Skip ]
 external/wpt/css/css-speech [ Skip ]
-external/wpt/css/filter-effects [ Skip ]
 external/wpt/css/tools [ Skip ]
 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/README [ Skip ]
 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/background [ Skip ]