Jquery UI 1.8.18 fails when used with Jquery 1.3.2 on IE8.

In the "position" module, the test for fraction support calls $(div).offset() with a function parameter. This only works on jQuery 1.4+. The end result of this is that on jQuery 1.3.2, the "top" css property ends up being set to 'NaNpx'. Sensible browsers ignore this, but IE8 throws an exception.