Refactor removal of trailing comma/period (#5434)

* Refactor removal of trailing comma/period

* Use regex

src/mfm/language.ts

@@ -167,10 +167,7 @@ export const mfmLanguage = P.createLanguage({
 				url = match[0];
 			}
 			url = removeOrphanedBrackets(url);
-			while (url.endsWith('.') || url.endsWith(',')) {
-				if (url.endsWith('.')) url = url.substr(0, url.lastIndexOf('.'));
-				if (url.endsWith(',')) url = url.substr(0, url.lastIndexOf(','));
-			}
+			url = url.replace(/[.,]*$/, '');
 			return P.makeSuccess(i + url.length, url);
 		}).map(x => createLeaf('url', { url: x }));
 	},