title: How to change text color of AppBar, icon color of FAB universally using theme?
body: <p>I am able to set the background color of <code>AppBar</code> to <code>Colors.amber</code>. This automatically sets the text color to Black. I am aware of the accessibility issues that may arise but anyways I want the text color to be White.</p>
  
  <p>I am still able to set the text color from the <code>AppBar</code> but I would like to set it universally.</p>
  
  <p>Here's the theme I'm using for my app.</p>
  
  <pre><code>title: 'Flutter Demo',
  theme: new ThemeData(
    primarySwatch: Colors.amber,
    textTheme: Theme.of(context).textTheme.apply(
      bodyColor: Colors.white,
      displayColor: Colors.white,
    ),
  ),
  </code></pre>