Page editing commands are registered with an NSUndoManager on Mac (and a similar mechanism on windows), but there’s no code to tell the NSUndoManager that these operations are no longer valid for Undoing once the page has been closed. This can lead to crashes downstream. In Radar as <rdar://problem/9482856>.
Created attachment 94335 [details]
Patch to clear edit commands in WebPageProxy::closePage()
Created attachment 94336 [details]
Same patch as last time but without Xcode-initiated tweak to project file.
Fixed in <http://trac.webkit.org/changeset/87030>.
I accidentally checked into a branch instead of trunk, rolled out in 87045.
Checked into tip of tree in http://trac.webkit.org/changeset/87046