src/vs/editor/standalone/browser/standaloneCodeEditorService.ts/StandaloneCodeEditorService/constructor
class StandaloneCodeEditorService:	constructor(
		@IContextKeyService contextKeyService: IContextKeyService,
		@IThemeService themeService: IThemeService,
	) {
		super(themeService);
		this.onCodeEditorAdd(() => this._checkContextKey());
		this.onCodeEditorRemove(() => this._checkContextKey());
		this._editorIsOpen = contextKeyService.createKey('editorIsOpen', false);
		this._activeCodeEditor = null;
	}