message: refactor(core): _reset() remove nextRecord
  The nextRecord is not neccessary, so remove it and use record._nextMoved to iterate
  PR Close
diff: @@ -236,7 +236,6 @@ export class DefaultIterableDiffer<V> implements IterableDiffer<V>, IterableChan
  _reset() {
  if (this.isDirty) {
  let record: IterableChangeRecord_<V>|null;
  - let nextRecord: IterableChangeRecord_<V>|null;
  for (record = this._previousItHead = this._itHead; record !== null; record = record._next) {
  record._nextPrevious = record._next;
  @@ -247,9 +246,8 @@ export class DefaultIterableDiffer<V> implements IterableDiffer<V>, IterableChan
  }
  this._additionsHead = this._additionsTail = null;
  - for (record = this._movesHead; record !== null; record = nextRecord) {
  + for (record = this._movesHead; record !== null; record = record._nextMoved) {
  record.previousIndex = record.currentIndex;
  - nextRecord = record._nextMoved;
  }
  this._movesHead = this._movesTail = null;
  this._removalsHead = this._removalsTail = null;
  