ScrollTabView

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {

  @override
   Widget build(BuildContext context) {
      return new Scaffold(
        backgroundColor: Colors.black,
        body: new DefaultTabController(
              length: 3,
              child: new CustomScrollView(
                slivers: [
                  new SliverList(
                    delegate: new SliverChildListDelegate(
                      <Widget>[
                        new Container(
                          color: Colors.grey,
                          height: 300.0,
                        ),
                        new TabBar(
                          tabs: [
                            new Tab(text: "Tab1"),
                            new Tab(text: "Tab2"),
                            new Tab(text: "Tab3"),
                          ],
                        ),
                        new Container(
                          height: 200.0,
                          child: new TabBarView(
                            children: <Widget>[
                              new Container(
                                color: Colors.red,
                                height: 300.0,
                              ),
                              new Container(
                                color: Colors.green,
                                height: 300.0,
                              ),
                              new Container(
                                color: Colors.yellow,
                                height: 300.0,
                              ),
                            ],
                          ),
                        )
                      ]
                    ),
                  )
                ]
              )
            ) 
      );
   }
}

如何定义TabBar的height呢