function isElementUpgraded_(element, jsClass) {
	    var upgradedList = getUpgradedListOfElement_(element);
	    return upgradedList.indexOf(jsClass) !== -1;
	  }
Store strings for class names defined by this component that are used in
JavaScript. This allows us to simply change it in one place should we
decide to modify at a later date.

@enum {string}
@private