In this case from plugins/unavailable-plugin-indicator-obscurity.html:
<embed id="pointerEventsBlockedOnObscuringSibling" class="shouldNotBeObscured" type="application/x-webkit-test-netscape"></embed>
<div class="cover" style="pointer-events: none;"></div>
div.cover completely obscures the embed, but because div.cover has pointer-events: none, the embed passes the hit-test in isReplacementObscured, and we claim that it isn't.
I'm going to post a patch to swap the expected behavior in the test, and leave this bug open to track fixing it (which I don't plan to nor know how to do).
Created attachment 207871 [details]
patch to change the test expectations
Changed the expected outcome of the test in http://trac.webkit.org/changeset/153536, but the bug still exists.