GitLab

Still need to investigate when this might happen and how to fix it,
but this will allow it to just break accessibility rather than crashing
the whole browser in the meantime.

BUG=161726


Review URL: https://chromiumcodereview.appspot.com/11787024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175470 0039d316-1c4b-4281-b951-d872f2087c98