Stack trace: ASSERTION FAILED: !childItemWithTarget(child->target()) /Users/rniwa/webkit/Source/WebCore/history/HistoryItem.cpp(463) : void WebCore::HistoryItem::addChildItem(WTF::PassRefPtr<WebCore::HistoryItem>) 1 0x10237b9ff WebCore::HistoryItem::addChildItem(WTF::PassRefPtr<WebCore::HistoryItem>) 2 0x10237967f WebCore::HistoryController::createItemTree(WebCore::Frame*, bool) 3 0x1023797b3 WebCore::HistoryController::pushState(WTF::PassRefPtr<WebCore::SerializedScriptValue>, WTF::String const&, WTF::String const&) 4 0x1023775de WebCore::History::stateObjectAdded(WTF::PassRefPtr<WebCore::SerializedScriptValue>, WTF::String const&, WTF::String const&, WebCore::History::StateObjectType, int&) 5 0x102675540 WebCore::JSHistory::pushState(JSC::ExecState*) 6 0x10267403b WebCore::jsHistoryPrototypeFunctionPushState(JSC::ExecState*) 7 0x326bb7601218 8 0x1000f1aac JSC::JITCode::execute(JSC::RegisterFile*, JSC::ExecState*, JSC::JSGlobalData*) 9 0x1000e80fe JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 10 0x100062257 JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 11 0x102578ec2 WebCore::JSMainThreadExecState::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) 12 0x102653767 WebCore::JSEventListener::handleEvent(WebCore::ScriptExecutionContext*, WebCore::Event*) 13 0x10228ae84 WebCore::EventTarget::fireEventListeners(WebCore::Event*, WebCore::EventTargetData*, WTF::Vector<WebCore::RegisteredEventListener, 1ul>&) 14 0x10228b3ca WebCore::EventTarget::fireEventListeners(WebCore::Event*) 15 0x1029b8b45 WebCore::Node::handleLocalEvents(WebCore::Event*) 16 0x10226e145 WebCore::EventDispatcher::dispatchEvent(WTF::PassRefPtr<WebCore::Event>) 17 0x1029a4b3f WebCore::MouseEventDispatchMediator::dispatchEvent(WebCore::EventDispatcher*) const 18 0x10226d4cb WebCore::EventDispatcher::dispatchEvent(WebCore::Node*, WTF::PassRefPtr<WebCore::EventDispatchMediator>) 19 0x1029b875b WebCore::Node::dispatchMouseEvent(WebCore::PlatformMouseEvent const&, WTF::AtomicString const&, int, WebCore::Node*) 20 0x1022777c7 WebCore::EventHandler::dispatchMouseEvent(WTF::AtomicString const&, WebCore::Node*, bool, int, WebCore::PlatformMouseEvent const&, bool) 21 0x10227898b WebCore::EventHandler::handleMouseReleaseEvent(WebCore::PlatformMouseEvent const&) 22 0x10227fdff WebCore::EventHandler::mouseUp(NSEvent*) 23 0x100be4764 -[WebHTMLView mouseUp:] 24 0x7fff82538431 -[NSWindow sendEvent:] 25 0x7fff89ce121a -[Window sendEvent:] 26 0x7fff89ade0ab -[BrowserWindow sendEvent:] 27 0x7fff8246dafa -[NSApplication sendEvent:] 28 0x7fff89a843cd -[BrowserApplication sendEvent:] 29 0x7fff824046de -[NSApplication run] 30 0x7fff823fd3b0 NSApplicationMain 31 0x7fff89c3fb3c SafariMain
*** This bug has been marked as a duplicate of bug 51224 ***