diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/preferences/fontbuilder.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/preferences/fontbuilder.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,89 @@
+// -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var FontBuilder = {
+  _enumerator: null,
+  get enumerator ()
+  {
+    if (!this._enumerator) {
+      this._enumerator = Components.classes["@mozilla.org/gfx/fontenumerator;1"]
+                                   .createInstance(Components.interfaces.nsIFontEnumerator);
+    }
+    return this._enumerator;
+  },
+
+  _allFonts: null,
+  buildFontList: function (aLanguage, aFontType, aMenuList) 
+  {
+    // Reset the list
+    while (aMenuList.hasChildNodes())
+      aMenuList.removeChild(aMenuList.firstChild);
+    
+    var defaultFont = null;
+    // Load Font Lists
+    var fonts = this.enumerator.EnumerateFonts(aLanguage, aFontType, { } );
+    if (fonts.length > 0)
+      defaultFont = this.enumerator.getDefaultFont(aLanguage, aFontType);
+    else {
+      fonts = this.enumerator.EnumerateFonts(aLanguage, "", { });
+      if (fonts.length > 0)
+        defaultFont = this.enumerator.getDefaultFont(aLanguage, "");
+    }
+    
+    if (!this._allFonts)
+      this._allFonts = this.enumerator.EnumerateAllFonts({});
+    
+    // Build the UI for the Default Font and Fonts for this CSS type.
+    var popup = document.createElement("menupopup");
+    var separator;
+    if (fonts.length > 0) {
+      if (defaultFont) {
+        var bundlePreferences = document.getElementById("bundlePreferences");
+        var label = bundlePreferences.getFormattedString("labelDefaultFont", [defaultFont]);
+        var menuitem = document.createElement("menuitem");
+        menuitem.setAttribute("label", label);
+        menuitem.setAttribute("value", ""); // Default Font has a blank value
+        popup.appendChild(menuitem);
+        
+        separator = document.createElement("menuseparator");
+        popup.appendChild(separator);
+      }
+      
+      for (var i = 0; i < fonts.length; ++i) {
+        menuitem = document.createElement("menuitem");
+        menuitem.setAttribute("value", fonts[i]);
+        menuitem.setAttribute("label", fonts[i]);
+        popup.appendChild(menuitem);
+      }
+    }
+    
+    // Build the UI for the remaining fonts. 
+    if (this._allFonts.length > fonts.length) {
+      // Both lists are sorted, and the Fonts-By-Type list is a subset of the
+      // All-Fonts list, so walk both lists side-by-side, skipping values we've
+      // already created menu items for. 
+      var builtItem = separator ? separator.nextSibling : popup.firstChild;
+      var builtItemValue = builtItem ? builtItem.getAttribute("value") : null;
+
+      separator = document.createElement("menuseparator");
+      popup.appendChild(separator);
+      
+      for (i = 0; i < this._allFonts.length; ++i) {
+        if (this._allFonts[i] != builtItemValue) {
+          menuitem = document.createElement("menuitem");
+          menuitem.setAttribute("value", this._allFonts[i]);
+          menuitem.setAttribute("label", this._allFonts[i]);
+          popup.appendChild(menuitem);
+        }
+        else {
+          builtItem = builtItem.nextSibling;
+          builtItemValue = builtItem ? builtItem.getAttribute("value") : null;
+        }
+      }
+    }
+    aMenuList.appendChild(popup);    
+  }
+};