Internet Explorer silently fails all calls to <node>.hasAttribute, which causes Review Board's line-comment system to fail.  A decent workaround is to use getAttribute instead, as that will return either null or "" when the attribute doesn't exist (depending on the DOM implementation), which are both boolean-false.

This fix was suggested by Mark Dewing in issue 261.

I verified that comments work on the following platforms:
    RHEL5, Firefox 2.0.0.4
    WinXP, Firefox 2.0.0.11
    WinXP, Internet Explorer 6.0 SP2
    Vista, Internet Explorer 7.0