anchor.diff:      const title = Text('Dart DevTools');
       Widget flexibleSpace;
       Size preferredSize;
  +    TabBar tabBar;
  +
       if (widget.tabs.length > 1) {
  -      final tabs = TabBar(
  +      tabBar = TabBar(
           controller: _tabController,
           isScrollable: true,
           onTap: _pushScreenToLocalPageRoute,
  
positive.code:       );
        preferredSize = Tween<Size>(
          begin: Size.fromHeight(kToolbarHeight),
          end: Size.fromHeight(kToolbarHeight + tabs.preferredSize.height),
        ).evaluate(appBarCurve);
        final animatedAlignment = Tween<Alignment>(
          begin: Alignment.centerRight,
          end: Alignment.bottomCenter,
        ).evaluate(appBarCurve);
        final animatedRightPadding = Tween<double>(
          begin:
              DevToolsScaffold.actionWidgetSize * (widget.actions?.length ?? 0.0),
          end: 0.0,
        ).evaluate(appBarCurve);
        flexibleSpace = Align(
          alignment: animatedAlignment,
          child: Padding(
  
negative.code:     );
  
      if (flexibleSpace == null) return appBar;
  
      return PreferredSize(
        key: isNarrow
            ? DevToolsScaffold.narrowWidthKey
  