Add crash expectation for...

Add crash expectation for third_party/blink/web_tests/external/wpt/webcodecs/video-decoder.html on Linux

TBR=chcunningham@chromium.org

Bug: 1121015, 1120431
Change-Id: I92a35847d27b6893bd99e9a27fe25dc1233c0406
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370883
Commit-Queue: Alice Boxhall <aboxhall@chromium.org>
Reviewed-by: Alice Boxhall <aboxhall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800894}

third_party/blink/web_tests/TestExpectations

@@ -6708,3 +6708,5 @@ crbug.com/1117613 media/video-error-networkState.html [ Failure Timeout ]
 # Sheriff 2020-0-21
 crbug.com/1120330 virtual/threaded/external/wpt/feature-policy/experimental-features/vertical-scroll-disabled-scrollbar-tentative.html [ Pass Failure ]
 
+# Sheriff 2020-08-24
+crbug.com/1121015 [ Linux ] external/wpt/webcodecs/video-decoder.html [ Pass Crash ]