Calling window.close() should indicate failure with warning message

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 5354c67cee624e87d8a82bd76d0ba859f61202c6..dc4372c1c05f4f4db3b037be0399c981f878aaeb 100644
--- a/Source/core/frame/DOMWindow.cpp
+++ b/Source/core/frame/DOMWindow.cpp
@@ -892,8 +892,10 @@ void DOMWindow::close(ExecutionContext* context)
     Settings* settings = m_frame->settings();
     bool allowScriptsToCloseWindows = settings && settings->allowScriptsToCloseWindows();
 
-    if (!(page->openedByDOM() || page->backForward().backForwardListCount() <= 1 || allowScriptsToCloseWindows))
+    if (!(page->openedByDOM() || page->backForward().backForwardListCount() <= 1 || allowScriptsToCloseWindows)) {
+        pageConsole()->addMessage(JSMessageSource, WarningMessageLevel, "Scripts may close only the windows that were opened by it.");
         return;
+    }
 
     if (!m_frame->loader().shouldClose())
         return;