Webkit: .is(':visible') is false for new nodes

[genezys]

Every other browsers returns true when testing .is(':visible') on newly created nodes (like $('<div/>')). WebKit returns false.

So methods that works with .filter(':visible') don't work on new nodes like .hide().

Test case:

$('<p>Should not be visible</p>').hide().appendTo(document.body);

The problem is real because the workaround is to append the nodes in the document and hide them after resulting in a huge performance hit for large trees.

[john]

Duplicate of #1239.