NoIssue - expose info about slow filters

    return obj;

  }

  const convertFilter = convertObject.bind(null, ["text"]);

  const convertFilterText = (text) => convertFilter({text});

  // pollute a converted filter object with `isSlow` detail

  // there are 3 kind of slow filters

  //  1. filter instanceof RegExpFilter && defaultMatcher.isSlowFilter(filter)

  //  2. filter instanceof ElemHideEmulationFilter

  //  3. filter instanceof SnippetFilter

  // for the time being, we want to simply expose the first kind

  // since there's nothing users can do to avoid others being slow

  function convertFilter(filter)

  {

    const obj = convertObject(["text"], filter);

    obj.isSlow = filter instanceof RegExpFilter &&

                  defaultMatcher.isSlowFilter(filter);

    return obj;

  }

  const convertFilterText = (text) => convertFilter({text});

  const uiPorts = new Map();

  const listenedPreferences = Object.create(null);

  const listenedFilterChanges = Object.create(null);