--- a/toolkit/content/Geometry.jsm
+++ b/toolkit/content/Geometry.jsm
@@ -133,16 +133,20 @@ let Util = {
     return gIOService.newURI(aURL, aOriginCharset, aBaseURI);
   },
 
   makeURLAbsolute: function makeURLAbsolute(base, url) {
     // Note:  makeURI() will throw if url is not a valid URI
     return this.makeURI(url, null, this.makeURI(base)).spec;
   },
 
+  isLocalScheme: function isLocalScheme(aURL) {
+    return (aURL.indexOf("about:") == 0 && aURL != "about:blank") || aURL.indexOf("chrome:") == 0;
+  },
+
   clamp: function(num, min, max) {
     return Math.max(min, Math.min(max, num));
   },
 
   /**
    * Determines whether a home page override is needed.
    * Returns:
    *  "new profile" if this is the first run with a new profile.