Add a Crash expectation for a custom-elements test

The new version of the test (not imported yet) trips a DCHECK. Since we
currently cannot rebaseline DCHECK failures, we have to mark the test as
Crash manually to unblock wpt-import.

TBR=domenic

No-Try: True
Bug: 805061
Change-Id: I58b7054eed776a63252610fc4afc7fbaf3a87a35
Reviewed-on: https://chromium-review.googlesource.com/882124Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531365}

third_party/WebKit/LayoutTests/TestExpectations

@@ -1749,6 +1749,8 @@ crbug.com/803558 external/wpt/websockets/opening-handshake/003-sets-origin.worke
 crbug.com/803200 external/wpt/websockets/cookies/006.html?wss [ Failure ]
 crbug.com/803200 external/wpt/websockets/opening-handshake/005.html?wss [ Pass Failure ]
 
+# DCHECK failure.
+crbug.com/805061 external/wpt/custom-elements/upgrading/Node-cloneNode.html [ Crash ]
 
 # ====== New tests from wpt-importer added here ======
 crbug.com/626703 external/wpt/svg/path/closepath/segment-completing.svg [ Failure ]