Revert "Move close handling to windowClosed event"

This reverts commit b893e97ccf.

runelite-client/src/main/java/net/runelite/client/util/SwingUtil.java

@@ -216,16 +216,10 @@ public class SwingUtil
 
 				if (result == JOptionPane.OK_OPTION)
 				{
-					frame.dispose();
+					callback.run();
+					System.exit(0);
 				}
 			}
-
-			@Override
-			public void windowClosed(WindowEvent event)
-			{
-				callback.run();
-				System.exit(0);
-			}
 		});
 	}