Sort child properties last in widget instance creationsDRT-W1164

Sort child properties last in widget instance creations. This improves readability and plays nicest with UI as Code visualization in IDEs with UI as Code Guides in editors (such as IntelliJ) where Properties in the correct order appear clearly associated with the constructor call and separated from the children.

BAD:

return Scaffold(
  appBar: AppBar(
    title: Text(widget.title),
  ),
  body: Center(
    child: Column(
      children: <Widget>[
        Text(
          'You have pushed the button this many times:',
         ),
        Text(
          '$_counter',
          style: Theme.of(context).textTheme.display1,
         ),
      ],
      mainAxisAlignment: MainAxisAlignment.center,
    ),
    widthFactor: 0.5,
  ),
  floatingActionButton: FloatingActionButton(
    child: Icon(Icons.add),
    onPressed: _incrementCounter,
    tooltip: 'Increment',
  ),
);

GOOD:

return Scaffold(
  appBar: AppBar(
    title: Text(widget.title),
  ),
  body: Center(
    widthFactor: 0.5,
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Text(
          'You have pushed the button this many times:',
         ),
        Text(
          '$_counter',
          style: Theme.of(context).textTheme.display1,
         ),
      ],
    ),
  ),
  floatingActionButton: FloatingActionButton(
    onPressed: _incrementCounter,
    tooltip: 'Increment',
    child: Icon(Icons.add),
  ),
);

Exception: It's allowed to have parameter with a function expression after the child property.