title: Flutter button with icon and text looks odd
body: <p>I am trying to create a Flutter app that has a button with a text and icon as label, the icon being placed right of the text. The approach described in <a href="https://stackoverflow.com/questions/49442247/round-button-with-text-and-icon-in-flutter">this post</a> yields an odd looking button that seems expanded to the width of the app, see this image (link as I am not allowed to attach images):</p>
  
  <p><a href="https://i.stack.imgur.com/46eUH.png" rel="noreferrer">Button becomes wide when adding a Row widget as child</a></p>
  
  <p>It is not clear to me which layout widgets to use to tweak the text+image button to be formatted as the plain text button.</p>
  
  <p>The code for producing the above example:</p>
  
  <pre><code>Widget build(BuildContext context) {
      return new Scaffold(
        appBar: new AppBar(
          title: new Text(widget.title),
        ),
        body: new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: &lt;Widget&gt;[
              new Text(
                'You have pushed the button this many times:',
              ),
              new Text(
                '$_counter',
                style: Theme.of(context).textTheme.display1,
              ),
              new RaisedButton(
                onPressed: _incrementCounter,
                child: new Row(
                  children: &lt;Widget&gt;[
                    new Text("Button with text and icon!"),
                    new Icon(Icons.lightbulb_outline)
                  ],
                ),
              ),
              new RaisedButton(
                onPressed: _incrementCounter,
                child: new Text("Button with only text")
                ),
            ],
          ),
        ),
        floatingActionButton: new FloatingActionButton(
          onPressed: _incrementCounter,
          tooltip: 'Increment',
          child: new Icon(Icons.add),
        ),
      );
    }
  }
  </code></pre>