only set overflow in $.fn.animate when the default overflow is visible

[hugodevreugd]

When you have a hidden div in IE8 with CSS overflow:auto, and a height set in CSS less than the height of the div (so it will get scroll bars when displayed). Then when you use $("#thediv").show(); jQuery 1.4.3.rc1 displays the div correctly with scroll bars, but when you use $("#thediv").show("slow"); jQuery 1.4.3.rc1 displays the div incorrectly without any scroll bars. In 1.4.2 scroll bars are displayed correctly in both cases. Other browser like FireFox or Chrome did display the scroll bars in jQuery 1.4.3.rc1 in both cases.

[snover]

IE8 functions the same as all other modern browsers: the overflow attribute of an element with an animated width or height is set to hidden until after the animation is complete in order to prevent content from overflowing during animations.

In IE6 and IE7, the overflow value remains hidden after the animation is complete because these browsers shrink wrap content in an element with layout. If you are running IE8 in IE7 mode, this is probably what you are experiencing.

We should probably only set overflow when the default overflow is not visible.

[snover]

Resetting milestone to future.

[Timmy Willison]

Duplicate of #3986.