Try to run in full screen on tablets

Using `bowser` to detect tablets, and type of browser to call either `webkitRequestFullScreen()` or `mozRequestFullScreen()`

Full screen request must happen in reponse to a user-action, so it’s included in the ‘try-it’ handler for the preview modal.

src/containers/preview-modal.jsx

@@ -3,6 +3,8 @@ import PropTypes from 'prop-types';
 import React from 'react';
 import {connect} from 'react-redux';
 
+import tabletFullScreen from '../lib/tablet-full-screen';
+
 import PreviewModalComponent from '../components/preview-modal/preview-modal.jsx';
 import BrowserModalComponent from '../components/browser-modal/browser-modal.jsx';
 import supportedBrowser from '../lib/supported-browser';
@@ -27,6 +29,8 @@ class PreviewModal extends React.Component {
     }
     handleTryIt () {
         this.setState({previewing: true});
+        // try to run in fullscreen mode on tablets.
+        tabletFullScreen();
         this.props.onTryIt();
     }
     handleCancel () {

src/lib/tablet-full-screen.js

+import bowser from 'bowser';
+
+/**
+ * Helper method to request full screen in the browser when on a tablet.
+ */
+export default function () {
+    if (bowser.tablet) {
+        if (bowser.webkit || bowser.blink) {
+            document.documentElement.webkitRequestFullScreen();
+        }
+        if (bowser.gecko) {
+            document.documentElement.mozRequestFullScreen();
+        }
+    }
+}