This test reproduces the crash in DOMWindow::clearTimeout that happens when DOMWindow is disconnected from the Frame (as in back/forward cache expiration case tested here).
This is the link to the bug: https://bugs.webkit.org/show_bug.cgi?id=29832
To reproduce the crash, click the link below, the popup window opens, which will immediately navigate to another one, so the b/f cache entry will be created. Close the popup window. Wait a few seconds (~10), for the page cache to start deleting pages it doesn't need - crash will happen.