function getRawComment(commentNode) {
	// in esprima, there's a 'raw' property, in babylon, the 'raw' string has to be reconstructed from the 'value' by adding the markers
	return commentNode ? commentNode.raw || '/*' + commentNode.value + '*/' : '';
}
Determines the raw comment string (source code form, including leading and trailing comment markers / *...* /) from a comment node.
Works for Esprima and Babylon based JSDoc versions.
@param {ASTNode} commentNode Node that contains the comment.
@returns {string} Comment string as written in the source