_newlineBreakability = function ( whiteSpace ) {

	switch ( whiteSpace ) {

		case 'pre':
		case 'pre-wrap':
		case 'pre-line':
			return 'mandatory';
	}

	// case NOWRAP:
	// case NORMAL:
	// default:

	return null;

}
Get the breakability of a newline character according to white-space property

@param whiteSpace
@returns {string|null}