regression from http://trac.webkit.org/changeset/58895 1) load any page 2) scroll a small amount 3) hover over the taskbar to bring up the window preview thumbnail --> preview is shown from the top of the page instead of from the scroll offset, and the scrolled offset is black. <rdar://problem/7959628>
Created attachment 55761 [details] patch
http://trac.webkit.org/changeset/59175