src/vs/platform/localizations/node/localizations.ts/LanguagePacksCache/update
class LanguagePacksCache:	update(extensions: ILocalExtension[]): Promise<{ [language: string]: ILanguagePack }> {
		return this.withLanguagePacks(languagePacks => {
			Object.keys(languagePacks).forEach(language => delete languagePacks[language]);
			this.createLanguagePacksFromExtensions(languagePacks, ...extensions);
		}).then(() => this.languagePacks);
	}