Element.tabIndex returns "undefined" for some elements, like <div>. All other browsers returns some value for it. For non "focusable" elements (like div), tabIndex should return a negative value (-1) by default (IE returns zero). For "focusable" elements (like input), it should return zero by default I'm attaching a TC that works well with Firefox and Opera.
Created attachment 23112 [details] TC This TC works well with Firefox and Opera.
<rdar://problem/6194013>
The test case returns expected values with TOT WebKit. Perhaps the wrong test case was attached, or maybe it was tested against an old version of WebKit.
For reference, this is the UA string with which I can still confirm this bug. Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Version/3.1.2 Safari/525.21 (Safari 3.1.2 Windows / 525.21)
So this is a duplicate of a bug we fixed.
*** This bug has been marked as a duplicate of 7138 ***