Remove css3/filters/effect-reference-external-stylesheet.html expectation

Appears to run stable now. (Maybe some risk for timeout on certain debug
bots.)

Tbr: schenney@chromium.org
Bug: 658305
Change-Id: Ib8f73e6470642339e27c96da3c192f1e952998ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2053805Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#741053}

third_party/blink/web_tests/TestExpectations

@@ -279,7 +279,6 @@ crbug.com/968791 virtual/scalefactor200/external/wpt/css/filter-effects/filters-
 crbug.com/658305 [ Mac ] virtual/scalefactor200/css3/filters/effect-all-on-background-hw.html [ Failure Pass ]
 crbug.com/968791 [ Win10 ] virtual/scalefactor200/css3/filters/effect-contrast-hw.html [ Failure ]
 crbug.com/658305 [ Mac ] virtual/scalefactor200/css3/filters/effect-reference-colorspace-hw.html [ Failure Pass ]
-crbug.com/658305 virtual/scalefactor200/css3/filters/effect-reference-external-stylesheet.html [ Failure Pass ]
 crbug.com/658305 virtual/scalefactor200/css3/filters/effect-reference-hw.html [ Failure Pass ]
 crbug.com/658305 virtual/scalefactor200/css3/filters/effect-reference-image-hw.html [ Failure Pass ]
 crbug.com/658305 virtual/scalefactor200/css3/filters/effect-reference-subregion-hw.html [ Failure Pass ]
@@ -2222,7 +2221,6 @@ crbug.com/377696 printing/setPrinting.html [ Failure ]
 
 crbug.com/658305 [ Mac ] css3/filters/buffer-offset.html [ Failure Pass ]
 crbug.com/658305 [ Mac ] css3/filters/effect-reference-external.html [ Failure Pass ]
-crbug.com/658305 css3/filters/effect-reference-external-stylesheet.html [ Failure Pass ]
 crbug.com/658305 css3/filters/effect-reference-image.html [ Pass Failure ]
 crbug.com/658305 css3/filters/effect-reference-image-lazy-attach.html [ Pass Failure ]
 crbug.com/658305 [ Mac ] css3/filters/effect-reference-subregion-chained.html [ Failure Pass ]