b717abdd changes some tests in chromium
b717abdd caused these test changes in chromium: https://chromium-layout-test-archives.storage.googleapis.com/results.html?json=chromium/try/linux-rel/1806971/blink_web_tests%20%28with%20patch%29/full_results_jsonp.js
It looks like these tests explicitly expect these to be errors, not warnings. I'm guessing these tests fall into the "documents with external subset or parameter entities" case, but I'd be worried about changing the behavior of chromium here.
Should these really be warnings, not errors? If so I might find a way to either re-interpret the warning and try to turn it back into an error or revert the patch in chromium.