code: function _isSmallerAfterCompression(rawFile, compressedFile, opts) {
      return compressedFile.remove()
          .then(function () {
              var tolerance = opts.tolerance < 1
                  ? opts.tolerance * rawFile.size
                  : opts.tolerance;
  
              return rawFile.size > compressedFile.size + tolerance;
          });
  }
docs: Checks whether the given raw file is smaller than the given compressed file
  Removes the compressed file
  @param {File} rawFile
  @param {File} compressedFile
  @param {Object}   [opts] -> lib/defaults.js
  @param {Number}   [opts.tolerance=0]
  @param {String[]} [opts.reporters=[]]
  @param {String}   [opts._tmpDir=md5]
  @returns {Promise * Boolean}