static getProperty (element) {
		var property = element.getAttribute("property") || element.getAttribute("itemprop");

		if (!property) {
			var multiple = element.getAttribute("mv-multiple");

			if (element.hasAttribute("property")) { // property used without a value
				property = multiple || element.name || element.id || element.classList[0];

				if (!property) {
					property = _.generatePropertyName(multiple === null? "prop" : "collection", element);
				}
			}
		}

		if (property) {
			element.setAttribute("property", property);
		}

		return property;
	}
Get & normalize property name, if exists