function determine_namespace_for_children(node, namespace) {
	if (node.name === 'foreignObject') {
		return 'html';
	}

	if (node.metadata.svg) {
		return 'svg';
	}

	return node.metadata.mathml ? 'mathml' : 'html';
}
Determines the namespace the children of this node are in.
@param {AST.RegularElement | AST.SvelteElement} node
@param {Namespace} namespace
@returns {Namespace}