Created attachment 62749 [details] repro I've attached two files that demonstrate an iframe using pushState() and back() to force navigation of the parent frame. The scripts work automatically on Chrome, but you can observe the same behavior with manual navigation in Safari. Based on my read of the standard we should be navigating the iframe's nested browsing context, not the top frame. This might be a regression from bug 36435.
Created attachment 62773 [details] simple fix (wip) Here's the fix. I still need to add a layout test, etc. I'm also thinking of changing createItemTree to return the target item as an out param so that we can avoid the recursive walk done by HistoryItem::targetItem().
Created attachment 62795 [details] v1 patch
Landed as http://trac.webkit.org/changeset/64369
http://trac.webkit.org/changeset/64369 might have broken Qt Linux Release