IE does not create an empty head element.

renderjs.js

@@ -905,6 +905,7 @@
     if (document_element.nodeType === 9) {
       settings.title = document_element.title;
 
+      if (document_element.head !== null) {
         for (i = 0; i < document_element.head.children.length; i += 1) {
           element = document_element.head.children[i];
           if (element.href !== null) {
@@ -920,13 +921,15 @@
               settings.required_js_list.push(
                 renderJS.getAbsoluteURL(element.getAttribute("src"), url)
               );
-          } else if (element.rel === "http://www.renderjs.org/rel/interface") {
+            } else if (element.rel ===
+                       "http://www.renderjs.org/rel/interface") {
               settings.interface_list.push(
                 renderJS.getAbsoluteURL(element.getAttribute("href"), url)
               );
             }
           }
         }
+      }
     } else {
       throw new Error("The first parameter should be an HTMLDocument");
     }