Remove some seemingly pointless code

Change-Id: Iee459685d229dc3758e6745cc0d1e6245bf9406b
Reviewed-on: http://gerrit.dmdirc.com/1434
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Gregory Holmes <greg@dmdirc.com>

src/com/dmdirc/addons/ui_swing/framemanager/tree/TreeFrameManager.java

     protected void checkRollover(final MouseEvent event) {
         NodeLabel node = null;
 
-        if (event == null) {
-            node = null;
-        } else if (tree.getNodeForLocation(event.getX(), event.getY())
-                != null) {
-            node =
-                    tree.getNodeForLocation(event.getX(), event.getY()).getLabel();
+        if (event != null && tree.getNodeForLocation(event.getX(), event.getY()) != null) {
+            node = tree.getNodeForLocation(event.getX(), event.getY()).getLabel();
         }
 
         synchronized (nodes) {
             for (TreeViewNode treeNode : nodes.values()) {
                 final NodeLabel label = treeNode.getLabel();
-                label.setRollover(node == null ? false : label == node);
+                label.setRollover(label == node);
             }
         }
         tree.repaint();