kill class props

examples/context/theme-detailed-app.js

@@ -11,11 +11,12 @@ function Toolbar(props) {
 }
 
 class App extends React.Component {
-  state = {
+  constructor(props) {
+    this.state = {
       theme: themes.light,
     };
   
-  toggleTheme = () => {
+    this.toggleTheme = () => {
       this.setState(state => ({
         theme:
           state.theme === themes.dark
@@ -23,6 +24,7 @@ class App extends React.Component {
             : themes.dark,
       }));
     };
+  }
 
   render() {
     //highlight-range{1-3}