[M91] Disable failing tests.

Only two-background-color-animation-diff-length3.html is marked as failing.

Sample failures: ci.chromium.org/ui/p/chromium/builders/ci/Linux%20Tests%20(dbg)(1)/95914/overview

(cherry picked from commit 77bef3c)

Bug: 1197444, 1197596
Change-Id: I991af5149aecf57632ec369bcb2dc37f69eb7cf5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2816958
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Tal Pressman <talp@google.com>
Cr-Original-Commit-Position: refs/heads/master@{#870903}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2824630
Commit-Queue: Oksana Zhuravlova <oksamyt@chromium.org>
Cr-Commit-Position: refs/branch-heads/4472@{#44}
Cr-Branched-From: 3d60439-refs/heads/master@{#870763}

third_party/blink/web_tests/TestExpectations

@@ -4765,6 +4765,9 @@ crbug.com/874837 [ Win ] ietestcenter/css3/bordersbackgrounds/background-attachm
 crbug.com/874931 virtual/threaded-prefer-compositing/fast/scroll-behavior/smooth-scroll/mousewheel-scroll.html [ Pass Failure Crash ]
 crbug.com/875003 [ Win ] editing/caret/caret-is-hidden-when-no-focus.html [ Pass Failure ]
 
+# Sheiff failures 2021-04-09
+crbug.com/1197444 [ Linux ] virtual/composite-bgcolor-animation/external/wpt/css/css-backgrounds/animations/two-background-color-animation-diff-length3.html [ Failure ]
+
 crbug.com/715718 external/wpt/media-source/mediasource-remove.html [ Failure Pass ]
 
 # New failure when importing css-variables: