Filters word combinations ending with certain function words.

@param {WordCombination[]} wordCombinations The word combinations to filter.
@param {array} functionWords The list of function words.
@returns {WordCombination[]} Filtered word combinations.
function filterFunctionWordsAtEnding( wordCombinations, functionWords ) {
	return wordCombinations.filter( function( combination ) {
		const words = combination.getWords();
		const lastWordIndex = words.length - 1;
		return ! includes( functionWords, words[ lastWordIndex ] );
	} );
}