Revert "Move close handling to windowClosed event"

This reverts commit b893e97ccf.

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

@@ -215,17 +215,11 @@ public class SwingUtil
 				}
 
 				if (result == JOptionPane.OK_OPTION)
-				{
-					frame.dispose();
-				}
-			}
-
-			@Override
-			public void windowClosed(WindowEvent event)
 				{
 					callback.run();
 					System.exit(0);
 				}
+			}
 		});
 	}