Remove trailing commas at the ends of initialiser lists. IE 8 and 9

didn't like them, which doesn't matter as such since they won't run
these JS puzzles anyway (no TypedArray support) but it hints that
other JS implementations might be picky about this too.

[originally from svn r9804]

emcclib.js

@@ -747,5 +747,5 @@ mergeInto(LibraryManager.library, {
      */
     js_focus_canvas: function() {
         onscreen_canvas.focus();
-    },
+    }
 });