anchor.diff:  
   import 'package:angular/angular.dart';
   import 'package:js/js.dart' as js;
  +import 'package:logging/logging.dart' show Logger;
   import 'package:angular_components/src/utils/angular/scroll_host/gestures.dart';
   import 'package:angular_components/src/utils/angular/scroll_host/pan_controller_impl.dart';
   import 'package:angular_components/src/utils/angular/scroll_host/position_sticky_controller.dart';
  
positive.code: 
  /// Base implementation of [ScrollHost] with common methods.
  abstract class ScrollHostBase implements ScrollHost {
    final DomService _domService;
    final NgZone _ngZone;
    PanController _panController;
  
negative.code:         // correct way to covert lines to pixels, but 16 pixels/line is works
          // reasonably well.
          int pixelsPerDeltaUnit = event.deltaMode == 0 ? 1 : 16;
          int deltaYPixels = deltaY.toInt() * pixelsPerDeltaUnit;
          _nativeOnScrollController.add(ScrollHostEventImpl(0, deltaYPixels));
        }));
      }
  