To reproduce: 1. Go to http://webkit.org/ 2. Right-click on the page and choose "Inspect Element" The Inspector's Elements panel is completely empty. Reloading fixes the problem (though you have to work around bug 26134 for now).
<rdar://problem/6940556>
Patch with the fix has been attached to https://bugs.webkit.org/show_bug.cgi?id=26134