Unregistering PNG mime support for quicktime in the QuickTime preferences panel fixes the regression.
The regression happened in http://trac.webkit.org/projects/webkit/changeset/16101
Quicktime should never render PNGS in the browser. WebKit should always render them. It's a bug that we're using the plugin at all.
*** Bug 11126 has been marked as a duplicate of this bug. ***
As Timothy Hatcher mentioned in http://bugs.webkit.org/show_bug.cgi?id=11126#c2 , when this test passes it still shows bug 5793.
Anders, could you talk a look at this?
Committed revision 17117.