src/validate/html/validateElement.js/getType
function getType ( validator, node ) {
	const attribute = node.attributes.find( attribute => attribute.name === 'type' );
	if ( !attribute ) return null;

	if ( attribute.value === true ) {
		validator.error( `'type' attribute must be specified`, attribute.start );
	}

	if ( attribute.value.length > 1 || attribute.value[0].type !== 'Text' ) {
		validator.error( `'type attribute cannot be dynamic`, attribute.start );
	}

	return attribute.value[0].data;
}