Return the first child of node matching an id reference.

def getElementById(self, node, id, default=join):
        """Return the first child of node matching an id reference."""
        attrget = self.getAttr
        ELEMENT_NODE = node.ELEMENT_NODE
        for child in node.childNodes:
            if child.nodeType == ELEMENT_NODE:
                if attrget(child, 'id') == id:
                    return child
        if default is not join:
            return default
        raise KeyError, name