Don't invokeandwait for no reason.

Issue CLIENT-251

Change-Id: Ie58644157e91e0a8244074145aa507818d96dc5e
Reviewed-on: http://gerrit.dmdirc.com/1961
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>

src/com/dmdirc/addons/ui_swing/MainFrame.java

     /** {@inheritDoc}. */
     @Override
     public void setTitle(final String title) {
-        if (title == null || getActiveFrame() == null) {
+        if (title == null || activeFrame == null) {
             super.setTitle(getTitlePrefix());
         } else {
             super.setTitle(getTitlePrefix() + " - " + title);