extensions/configuration-editing/src/settingsDocumentHelper.ts/SettingsDocument/provideLanguageCompletionItems
class SettingsDocument:	private provideLanguageCompletionItems(_location: Location, range: vscode.Range, formatFunc: (string: string) => string = (l) => JSON.stringify(l)): Thenable<vscode.CompletionItem[]> {
		return vscode.languages.getLanguages()
			.then(languages => languages.map(l => this.newSimpleCompletionItem(formatFunc(l), range)));
	}