Use ?. in a few more places

extensions/markdown-language-features/src/util/dispose.ts

@@ -8,9 +8,7 @@ import * as vscode from 'vscode';
 export function disposeAll(disposables: vscode.Disposable[]) {
 	while (disposables.length) {
 		const item = disposables.pop();
-		if (item) {
-			item.dispose();
-		}
+		item?.dispose();
 	}
 }
 
@@ -39,4 +37,4 @@ export abstract class Disposable {
 	protected get isDisposed() {
 		return this._isDisposed;
 	}
-}
+}