Don't fire popstate event on initial document load

Source/core/frame/DOMWindow.cpp

Index: Source/core/frame/DOMWindow.cpp
diff --git a/Source/core/frame/DOMWindow.cpp b/Source/core/frame/DOMWindow.cpp
index 5882fbf30fc29cec5170ccc23a4bf5b0b1a244a4..0b79cc9bfa316cc7357426b7534d5b0478aa0c59 100644
--- a/Source/core/frame/DOMWindow.cpp
+++ b/Source/core/frame/DOMWindow.cpp
@@ -450,7 +450,8 @@ void DOMWindow::documentWasClosed()
 {
     dispatchWindowLoadEvent();
     enqueuePageshowEvent(PageshowEventNotPersisted);
-    enqueuePopstateEvent(m_pendingStateObject ? m_pendingStateObject.release() : SerializedScriptValue::nullValue());
+    if (m_pendingStateObject)
+        enqueuePopstateEvent(m_pendingStateObject.release());
 }
 
 void DOMWindow::enqueuePageshowEvent(PageshowEventPersistence persisted)