Include Mac10.12 in crash expectation for harness-tests/crash.html.

BUG=697971

Review-Url: https://codereview.chromium.org/2745793005
Cr-Commit-Position: refs/heads/master@{#456189}

third_party/WebKit/LayoutTests/TestExpectations

 # Intentional failures to test the layout test system.
-Bug(intentional) [ Android Linux Win Mac10.10 Mac10.11 Retina ] harness-tests/crash.html [ Crash ]
+Bug(intentional) [ Android Linux Win Mac10.10 Mac10.11 Retina Mac10.12 ] harness-tests/crash.html [ Crash ]
 crbug.com/644303 [ Mac10.9 ] harness-tests/crash.html [ Crash Timeout ]
 Bug(intentional) harness-tests/timeout.html [ Timeout ]