getRootAncestor() {
		if (this.root === true) {
			return this;
		} else {
			let ancestor = this.ancestor;
			while (ancestor) {
				if (ancestor.root === true) {
					break;
				}
				ancestor = ancestor.ancestor;
			}
			return ancestor;
		}
	}
Returns the instance of the root container (i.e. the current application World container).
@returns {Container} root container