Make sure to perform the path completion steps if starting the path causes it to complete.

git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@375 ed5b42cb-e716-0410-a449-f6a68f950b19

src/as/com/threerings/flash/path/Path.as

@@ -137,7 +137,11 @@ public /*abstract*/ class Path
         if (_onStart != null) {
             _onStart(this);
         }
-        return tick(now);
+        var remain :int = tick(now);
+        if (remain <= 0) {
+           pathCompleted(false);
+        }
+        return remain;
     }
 
     /**