I'm seeing several talkback reports (TB23621344, TB23620975, TB23620475) with the same stack in current builds. The comments suggest this is dealing with alarm-firing. The stacks look fairly identical: js_SetProtoOrParent [mozilla\js\src\jsobj.c, line 341] JS_SetPrototype [mozilla\js\src\jsapi.c, line 2399] xpc_CloneJSFunction [mozilla\js\src\xpconnect\src\xpcwrappednativeinfo.cpp, line 77] DefinePropertyIfFound [mozilla\js\src\xpconnect\src\xpcwrappednativejsops.cpp, line 454] XPC_WN_ModsAllowed_Proto_Resolve [mozilla\js\src\xpconnect\src\xpcwrappednativejsops.cpp, line 1579] js_LookupPropertyWithFlags [mozilla\js\src\jsobj.c, line 3227] js_LookupProperty [mozilla\js\src\jsobj.c, line 3085] nsWindowSH::NewResolve [mozilla\dom\src\base\nsdomclassinfo.cpp, line 6004] XPC_WN_Helper_NewResolve [mozilla\js\src\xpconnect\src\xpcwrappednativejsops.cpp, line 1064] Filing as UNCO until we can get real steps to reproduce

It's actually a crash caused by one of dbaron's leak fix bugs (bug 353090). It should be fixed now, though. *** This bug has been marked as a duplicate of 353704 *** *** This bug has been marked as a duplicate of 353704 ***