src/vs/workbench/api/browser/mainThreadEditors.ts/MainThreadTextEditors/$trySetDecorations
class MainThreadTextEditors:	$trySetDecorations(id: string, key: string, ranges: IDecorationOptions[]): Promise<void> {
		key = `${this._instanceId}-${key}`;
		const editor = this._editorLocator.getEditor(id);
		if (!editor) {
			return Promise.reject(disposed(`TextEditor(${id})`));
		}
		editor.setDecorations(key, ranges);
		return Promise.resolve(undefined);
	}