src/vs/editor/standalone/browser/standaloneEditor.ts/setModelLanguage
export function setModelLanguage(model: ITextModel, languageId: string): void {
	const languageService = StandaloneServices.get(ILanguageService);
	const modelService = StandaloneServices.get(IModelService);
	modelService.setMode(model, languageService.createById(languageId));
}