--- a/dom/browser-element/BrowserElementChildPreload.js
+++ b/dom/browser-element/BrowserElementChildPreload.js
@@ -1119,16 +1119,23 @@ BrowserElementChild.prototype = {
     });
   },
 
   _mozExitDomFullscreen: function(e) {
     sendAsyncMsg("exit-dom-fullscreen");
   },
 
   _getContentDimensions: function() {
+    if (!content.document.body) {
+      return {
+        width: 0,
+        height: 0
+      }
+    }
+
     return {
       width: content.document.body.scrollWidth,
       height: content.document.body.scrollHeight
     }
   },
 
   /**
    * Actually take a screenshot and foward the result up to our parent, given