code: function replaceWithEmptyText(selector, specificity, regex, typeIndex) {
    return selector.replace(regex, function(match) {
      specificity[typeIndex] += 1;
      // Replace this simple selector with whitespace so it won't be counted
      // in further simple selectors.
      return Array(match.length + 1).join(' ');
    });
  }
docs: Find matches for a regular expression in the selector and increase count.
  @param {string} selector The selector to match the regex with.
  @param {!Array<number>} specificity The current specificity.
  @param {!RegExp} regex The regular expression.
  @param {number} typeIndex Index of type count.
  @return {string}