function isValidContainer(node) {
	  return !!(node && (node.nodeType === ELEMENT_NODE_TYPE || node.nodeType === DOC_NODE_TYPE || node.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE));
	}
True if the supplied DOM node is a valid node element.

@param {?DOMElement} node The candidate DOM node.
@return {boolean} True if the DOM is a valid DOM node.
@internal