anchor.diff:    /// This function is called only during the "active" lifecycle state.
     @mustCallSuper
     void update(@checked Widget newWidget) {
  -    assert(_debugLifecycleState == _ElementLifecycle.active);
  -    assert(widget != null);
  -    assert(newWidget != null);
  -    assert(newWidget != widget);
  -    assert(depth != null);
  -    assert(_active);
  -    assert(Widget.canUpdate(widget, newWidget));
  +    // This code is hot when hot reloading, so we try to
  +    // only call _AssertionError._evaluateAssertion once.
  +    assert(_debugLifecycleState == _ElementLifecycle.active
  +        && widget != null
  +        && newWidget != null
  +        && newWidget != widget
  +        && depth != null
  +        && _active
  +        && Widget.canUpdate(widget, newWidget));
       _widget = newWidget;
     }
   
  
positive.code:   bool _active = false;
  
    void _reassemble() {
      assert(_active);
      visitChildren((Element child) {
        child._reassemble();
      });
    }
  
    bool _debugIsInScope(Element target) {
      assert(target != null);
      if (target == this)
        return true;
      if (_parent != null)
        return _parent._debugIsInScope(target);
      return false;
    }
  
  
negative.code:   void scheduleBuildFor(BuildableElement element) {
      assert(element != null);
      assert(element.owner == this);
      assert(() {
        if (debugPrintScheduleBuildForStacks)
          debugPrintStack(label: 'scheduleBuildFor() called for $element${_dirtyElements.contains(element) ? " (ALREADY IN LIST)" : ""}');
  