--- a/extensions/pref/autoconfig/src/Makefile.in
+++ b/extensions/pref/autoconfig/src/Makefile.in
@@ -1,21 +1,7 @@
 # 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/.
 
 AUTOCFG_JS_EXPORTS = \
 		$(srcdir)/prefcalls.js \
 		$(NULL)
-
-ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
-AUTOCFG_JS_EXPORTS += $(srcdir)/mac/platform.js
-else
-ifeq ($(MOZ_WIDGET_TOOLKIT), windows)
-AUTOCFG_JS_EXPORTS += $(srcdir)/win/platform.js
-else
-ifeq ($(MOZ_WIDGET_TOOLKIT), beos)
-AUTOCFG_JS_EXPORTS += $(srcdir)/beos/platform.js
-else
-AUTOCFG_JS_EXPORTS += $(srcdir)/unix/platform.js
-endif
-endif
-endif

deleted file mode 100644
--- a/extensions/pref/autoconfig/src/beos/platform.js
+++ /dev/null
@@ -1,6 +0,0 @@
-/* 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/. */
-
-// BeOS specific auto configuration preference defaults
-platform.value = "beos";

deleted file mode 100644
--- a/extensions/pref/autoconfig/src/mac/platform.js
+++ /dev/null
@@ -1,6 +0,0 @@
-/* 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/. */
-
-// Mac specific auto configuration preference defaults
-platform.value = "macintosh";

--- a/extensions/pref/autoconfig/src/nsReadConfig.cpp
+++ b/extensions/pref/autoconfig/src/nsReadConfig.cpp
@@ -153,21 +153,16 @@ nsresult nsReadConfig::readConfigFile()
         if (NS_FAILED(rv))
             return rv;
         
         // Open and evaluate function calls to set/lock/unlock prefs
         rv = openAndEvaluateJSFile("prefcalls.js", 0, false, false);
         if (NS_FAILED(rv)) 
             return rv;
 
-        // Evaluate platform specific directives
-        rv = openAndEvaluateJSFile("platform.js", 0, false, false);
-        if (NS_FAILED(rv)) 
-            return rv;
-
         mRead = true;
     }
     // If the lockFileName is nullptr return ok, because no lockFile will be used
   
   
     // Once the config file is read, we should check that the vendor name 
     // is consistent By checking for the vendor name after reading the config 
     // file we allow for the preference to be set (and locked) by the creator 

--- a/extensions/pref/autoconfig/src/prefcalls.js
+++ b/extensions/pref/autoconfig/src/prefcalls.js
@@ -5,19 +5,16 @@
 
 const nsILDAPURL = Components.interfaces.nsILDAPURL;
 const LDAPURLContractID = "@mozilla.org/network/ldap-url;1";
 const nsILDAPSyncQuery = Components.interfaces.nsILDAPSyncQuery;
 const LDAPSyncQueryContractID = "@mozilla.org/ldapsyncquery;1";
 const nsIPrefService = Components.interfaces.nsIPrefService;
 const PrefServiceContractID = "@mozilla.org/preferences-service;1";
 
-// set on a platform specific basis in platform.js
-platform = { value: "" };
-
 var gVersion;
 
 function getPrefBranch() {
     
     var prefService = Components.classes[PrefServiceContractID]
                                 .getService(nsIPrefService);    
     return prefService.getBranch(null);
 }

deleted file mode 100644
--- a/extensions/pref/autoconfig/src/unix/platform.js
+++ /dev/null
@@ -1,6 +0,0 @@
-/* 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/. */
-
-// Unix specific auto configuration preference defaults
-platform.value = "unix";

deleted file mode 100644
--- a/extensions/pref/autoconfig/src/win/platform.js
+++ /dev/null
@@ -1,6 +0,0 @@
-/* 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/. */
-
-// Windows specific auto configuration preference defaults
-platform.value = "windows";