Pass in the expected type to readObject anywhere the code would clearly convert the wrong type to null anyway

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5440 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/as/com/threerings/presents/net/BootstrapNotification.as

@@ -33,7 +33,7 @@ public class BootstrapNotification extends DownstreamMessage
     override public function readObject (ins :ObjectInputStream) :void
     {
         super.readObject(ins);
-        _data = (ins.readObject() as BootstrapData);
+        _data = (ins.readObject(BootstrapData) as BootstrapData);
     }
 
     /** The data associated with this notification. */