anchor.diff:  
     Scrollable({
       Key key,
  +    this.initialScrollOffset,
       this.scrollDirection: ScrollDirection.vertical
     }) : super(key: key) {
       assert(scrollDirection == ScrollDirection.vertical ||
              scrollDirection == ScrollDirection.horizontal);
     }
   
  +  double initialScrollOffset;
     ScrollDirection scrollDirection;
   
     AnimatedSimulation _toEndAnimation; // See _startToEndAnimation()
     ValueAnimation<double> _toOffsetAnimation; // Started by scrollTo()
   
     void initState() {
  +    if (initialScrollOffset is double)
  +      _scrollOffset = initialScrollOffset;
       _toEndAnimation = new AnimatedSimulation(_setScrollOffset);
       _toOffsetAnimation = new ValueAnimation<double>()
         ..addListener(() {
  
positive.code:     this.curve: ease
    }) : super(
      key: key,
      scrollDirection: scrollDirection,
      items: items,
      itemBuilder: itemBuilder,
  
negative.code: class ScrollableList<T> extends ScrollableWidgetList {
    ScrollableList({
      Key key,
      double initialScrollOffset,
      ScrollDirection scrollDirection: ScrollDirection.vertical,
      this.items,
      this.itemBuilder,
      this.itemsWrap: false,
      double itemExtent,
      EdgeDims padding
    }) : super(
      key: key,
      initialScrollOffset: initialScrollOffset,
      scrollDirection: scrollDirection,
      itemExtent: itemExtent,
      padding: padding);
  
    List<T> items;
    ItemBuilder<T> itemBuilder;
  