protected function normalizeNode(DOMNode $node)
	{
		if (!$node->parentNode)
		{
			// Ignore nodes that have been removed from the document
			return;
		}
		if ($node instanceof DOMElement)
		{
			$this->normalizeElement($node);
		}
		elseif ($node instanceof DOMAttr)
		{
			$this->normalizeAttribute($node);
		}
	}