title: Simple string title is not updating when using hot reload
body: <p><strong>Hot reload</strong> is not working in a simple <code>Hello World</code> example. When trying to change the <code>text</code>, a <code>string</code>, to something else under run-time and hot reload it, nothing happens. I'm debugging on a <em>physical</em> device and I'm using <em>VSCode</em>. </p>
  
  <pre><code>import 'package:flutter/material.dart';
  
  void main() {
    String text = "Hello world";
        runApp(Center(child: new Text(text, textDirection: TextDirection.ltr)));
  }
  </code></pre>
  
  <p>Is <strong>hot reload</strong> not reliable or am i doing something wrong here? </p>
  
  <p><em>EDIT: Found out that restarting the app, CTRL+SHIFT+F5, worked as the hot reload should.</em> </p>