Created attachment 128652 [details] Testcase See attached testcase. There should be no red.
Duplicate of bug 46800?
At first glance in WebKit it may be sort of a duplicate of the querySelector thing (insofar as the code is shared) but not of getElementsByTagName... Note that making this work would take more work than making querySelector work, though.
Follow up with your test in https://bugs.webkit.org/show_bug.cgi?id=140930 Thanks for reporting this bug Boris. *** This bug has been marked as a duplicate of bug 140878 ***