anchor.diff:  ///
   /// See <https://developer.mozilla.org/en-US/docs/Web/API/UIEvent>
   @JS()
  +// TODO make @anonymous once https://github.com/dart-lang/sdk/issues/43939 is fixed
   class SyntheticUIEvent extends SyntheticEvent {
     /// [SyntheticUIEvent]s cannot be manually instantiated.
     ///
  
positive.code: ///
  /// See <https://developer.mozilla.org/en-US/docs/Web/API/AnimationEvent>
  @JS()
  class SyntheticAnimationEvent extends SyntheticEvent {
    /// [SyntheticAnimationEvent]s cannot be manually instantiated.
    ///
  
negative.code: ///
  /// See <https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent>
  @JS()
  // TODO make @anonymous once https://github.com/dart-lang/sdk/issues/43939 is fixed
  class SyntheticMouseEvent extends SyntheticEvent {
    /// [SyntheticMouseEvent]s cannot be manually instantiated.
    ///
  