WebKit2 snapshots miss the contents of composited iframes.
For example load LayoutTests/compositing/composited-parent-iframe.html and view All History in Safari.
<rdar://problem/9021331>
Created attachment 82886 [details] Patch
http://trac.webkit.org/changeset/78946
http://trac.webkit.org/changeset/78946 might have broken GTK Linux 32-bit Debug