Fix expectation for flaky test.

Bug: 809998
Change-Id: I2cd1ca2b81a066fcb344a8a2861e9bd5e0ca2a1c
TBR: wolenetz@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/906929
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535022}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2463,7 +2463,7 @@ crbug.com/678499 http/tests/security/contentSecurityPolicy/require-sri-for/requi
 
 crbug.com/747751 [ Win ] http/tests/devtools/application-panel/resources-panel-resource-preview.js [ Failure Pass ]
 
-crbug.com/689781 external/wpt/media-source/mediasource-duration.html [ Failure Pass ]
+crbug.com/689781 external/wpt/media-source/mediasource-duration.html [ Failure Pass Crash ]
 
 # Rebaseline for v8's --harmony-function-tostring
 crbug.com/753073 fast/dom/TreeWalker/acceptNode-filter.html [ NeedsManualRebaseline ]
@@ -3218,7 +3218,6 @@ crbug.com/806017 [ Linux ] virtual/gpu/fast/canvas/canvas-strokePath-shadow.html
 crbug.com/809152 netinfo/estimate-multiple-frames.html [ Pass Failure ]
 
 # Sheriff failures 2018-02-07
-crbug.com/809998 [ Linux ] external/wpt/media-source/mediasource-duration [ Pass Crash Failure ]
 crbug.com/810009 [ Linux ] paint/invalidation/image/canvas-composite-repaint-by-all-imagesource.html [ Pass Timeout ]
 crbug.com/810009 [ Linux ] virtual/spv175/paint/invalidation/image/canvas-composite-repaint-by-all-imagesource.html [ Pass Timeout ]