\MathQuillMathField{} should only be used in static math #cleanup

...not editable math field.
diff --git a/test/unit/updown.test.js b/test/unit/updown.test.js
index 5e433c5..667e1a6 100644
--- a/test/unit/updown.test.js
+++ b/test/unit/updown.test.js
@@ -175,7 +175,7 @@
   });
 
   test('\\MathQuillMathField{} in a fraction', function() {
-    var outer = MQ.MathField(
+    var outer = MQ.StaticMath(
       $('<span>\\frac{\\MathQuillMathField{n}}{2}</span>').appendTo('#mock')[0]
     );
     var inner = MQ($(outer.el()).find('.mq-editable-field')[0]);