code: function startWatchingForValueChange(target, targetInst) {
    activeElement = target;
    activeElementInst = targetInst;
    activeElement.attachEvent('onpropertychange', handlePropertyChange);
  }
docs: (For IE <=9) Starts tracking propertychange events on the passed-in element
  and override the value property so that we can distinguish user events from
  value changes in JS.