You need to
before you can comment on or make changes to this bug.
Gecko removed it in https://bugzilla.mozilla.org/show_bug.cgi?id=687400 and it will soon be expunged from DOM4 as per: http://lists.w3.org/Archives/Public/public-webapps/2011JulSep/1361.html
As mentioned in the Gecko bug, there is quite a number of uses found by code search. And there is already a report of site brokenness.
It's clear that this method causes confusion, but it's quite harmless (minor performance degradation when compared to using ===).