Adds Google platform.js script to index.php (#882)

client/src/index.php

@@ -25,6 +25,7 @@
             globalIndexPath = "<?=$path ?>";
             showLogs = false;
         </script>
+        <script src="https://apis.google.com/js/platform.js" async defer></script>
         <?php if (preg_match('~MSIE|Internet Explorer~i', $_SERVER['HTTP_USER_AGENT']) || (strpos($_SERVER['HTTP_USER_AGENT'], 'Trident/7.0; rv:11.0') !== false)): ?>
           <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=String.prototype.startsWith,Array.from,Array.prototype.fill,Array.prototype.keys,Array.prototype.find,Array.prototype.findIndex,Array.prototype.includes,String.prototype.repeat,Number.isInteger,Promise&flags=gated"></script>
         <?php endif; ?>