Use .?method() in more places (#152112)

Switches simple patterns like:

```ts
if (some.thing) {
    some.thing.method();
}
```

to:

```ts
some.thing?.method()
```

This is more concise and avoids having to repeat the `some.thing` part

src/vs/workbench/services/textMate/browser/textMateWorker.ts

@@ -214,9 +214,7 @@ export class TextMateWorker {
 
 	public async acceptTheme(theme: IRawTheme, colorMap: string[]): Promise<void> {
 		const grammarFactory = await this._grammarFactory;
-		if (grammarFactory) {
-			grammarFactory.setTheme(theme, colorMap);
-		}
+		grammarFactory?.setTheme(theme, colorMap);
 	}
 
 	public _setTokens(resource: URI, versionId: number, tokens: Uint8Array): void {