code: function _concatNotDiffParts(diff) {
      for (var i = 1; i < diff.length; i++) {
          var currPart = diff[i],
              prevPart = diff[i - 1];
  
          if (!_isDiffPart(currPart) && !_isDiffPart(prevPart)) {
              prevPart.value += currPart.value;
  
              diff.splice(i--, 1);
          }
      }
  
      return diff;
  }
docs: Concats not diff parts which go one by one
  @param {Diff[]} diff
  @returns {Diff[]}