Add feature detection test for classList

public/assets/enhancements.js

@@ -33,11 +33,12 @@
         && div.firstChild.namespaceURI
       ) == 'http://www.w3.org/2000/svg';
     })(),
-    querySelector: typeof document.querySelector === 'function'
+    querySelector: typeof document.querySelector === 'function',
+    classList: 'classList' in document.createElement('div')
   };
 
   // Check required features for favourite nodes
-  if(supports.localStorage && supports.inlineSVG && supports.querySelector) {
+  if(supports.localStorage && supports.inlineSVG && supports.querySelector && supports.classList) {
 
     // Get heart SVG
     var xhr = new XMLHttpRequest();
@@ -91,6 +92,7 @@
   }
 
   // Add ios class to body on iOS devices
+  if(supports.classList) {
     DOMReady(function() {
       if(
         /iPad|iPhone|iPod/.test(navigator.userAgent)
@@ -100,5 +102,6 @@
         document.body.classList.add('ios');
       }
     });
+  }
 
 })();