--- a/chat/modules/hiddenWindow.jsm
+++ b/chat/modules/hiddenWindow.jsm
@@ -30,17 +30,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-let EXPORTED_SYMBOLS = ["getHiddenHTMLWindow"];
+const EXPORTED_SYMBOLS = ["getHiddenHTMLWindow"];
 
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "hiddenWindow", function()
   Components.classes["@mozilla.org/appshell/appShellService;1"]
                       .getService(Components.interfaces.nsIAppShellService)
                       .hiddenDOMWindow
 );

--- a/chat/modules/http.jsm
+++ b/chat/modules/http.jsm
@@ -30,17 +30,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = ["doXHRequest"];
+const EXPORTED_SYMBOLS = ["doXHRequest"];
 
 const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
 
 Cu.import("resource:///modules/imXPCOMUtils.jsm");
 
 initLogModule("xhr", this);
 
 function doXHRequest(aUrl, aHeaders, aPOSTData, aOnLoad, aOnError, aThis) {

--- a/chat/modules/imContentSink.jsm
+++ b/chat/modules/imContentSink.jsm
@@ -32,17 +32,17 @@
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 Components.utils.import("resource:///modules/imServices.jsm");
 
-var EXPORTED_SYMBOLS = [
+const EXPORTED_SYMBOLS = [
   "cleanupImMarkup", // used to clean up incoming IMs.
                      // This will use the global ruleset of acceptable stuff
                      // except if another (custom one) is provided
   "createDerivedRuleset", // used to create a ruleset that inherits from the
                           // default one
                           // useful if you want to allow or forbid
                           // an additionnal thing in a specific
                           // conversation but take into account all

--- a/chat/modules/imServices.jsm
+++ b/chat/modules/imServices.jsm
@@ -30,17 +30,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-let EXPORTED_SYMBOLS = ["Services"];
+const EXPORTED_SYMBOLS = ["Services"];
 
 Components.utils.import("resource://gre/modules/Services.jsm");
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyServiceGetter(Services, "accounts",
                                    "@mozilla.org/chat/accounts-service;1",
                                    "imIAccountsService");
 XPCOMUtils.defineLazyServiceGetter(Services, "core",

--- a/chat/modules/imSmileys.jsm
+++ b/chat/modules/imSmileys.jsm
@@ -32,17 +32,17 @@
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 Components.utils.import("resource:///modules/imServices.jsm");
 
-var EXPORTED_SYMBOLS = [
+const EXPORTED_SYMBOLS = [
   "smileImMarkup", // used to add smile:// img tags into IM markup.
   "smileTextNode", // used to add smile:// img tags to the content of a textnode
   "smileString", // used to add smile:// img tags into a string without parsing it as HTML. Be sure the string doesn't contain HTML tags.
   "getSmileRealURI", // used to retrive the chrome URI for a smile:// URI
   "getSmileyList" // used to display a list of smileys in the UI
 ];
 
 const kEmoticonsThemePref = "messenger.options.emoticonsTheme";

--- a/chat/modules/imStatusUtils.jsm
+++ b/chat/modules/imStatusUtils.jsm
@@ -29,17 +29,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = ["Status"];
+const EXPORTED_SYMBOLS = ["Status"];
 
 Components.utils.import("resource:///modules/imServices.jsm");
 
 const imIStatusInfo = Components.interfaces.imIStatusInfo;
 let statusNames = {};
 statusNames[imIStatusInfo.STATUS_UNKNOWN] = "unknown";
 statusNames[imIStatusInfo.STATUS_OFFLINE] = "offline";
 statusNames[imIStatusInfo.STATUS_INVISIBLE] = "invisible";

--- a/chat/modules/imTextboxUtils.jsm
+++ b/chat/modules/imTextboxUtils.jsm
@@ -30,17 +30,21 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = ["MessageFormat", "TextboxSize", "TextboxSpellChecker"];
+const EXPORTED_SYMBOLS = [
+  "MessageFormat",
+  "TextboxSize",
+  "TextboxSpellChecker"
+];
 
 Components.utils.import("resource:///modules/imServices.jsm");
 const Ci = Components.interfaces;
 
 let MessageFormat = {
   _observedPrefs: [],
 
   getValues: function mf_getValues() {

--- a/chat/modules/imThemes.jsm
+++ b/chat/modules/imThemes.jsm
@@ -30,17 +30,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = [
+const EXPORTED_SYMBOLS = [
   "getCurrentTheme",
   "getThemeByName",
   "getHTMLForMessage",
   "getThemeVariants",
   "isNextMessage",
   "insertHTMLForMessage",
   "initHTMLDocument",
   "getMessagesForRange",

--- a/chat/modules/imXPCOMUtils.jsm
+++ b/chat/modules/imXPCOMUtils.jsm
@@ -31,17 +31,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = [
+const EXPORTED_SYMBOLS = [
   "XPCOMUtils",
   "setTimeout",
   "clearTimeout",
   "executeSoon",
   "hasOwnProperty",
   "nsSimpleEnumerator",
   "EmptyEnumerator",
   "ClassInfo",

--- a/chat/modules/jsProtoHelper.jsm
+++ b/chat/modules/jsProtoHelper.jsm
@@ -31,17 +31,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = [
+const EXPORTED_SYMBOLS = [
   "GenericAccountPrototype",
   "GenericAccountBuddyPrototype",
   "GenericConvIMPrototype",
   "GenericConvChatPrototype",
   "GenericConvChatBuddyPrototype",
   "GenericMessagePrototype",
   "GenericProtocolPrototype",
   "ForwardProtocolPrototype",

--- a/chat/modules/socket.jsm
+++ b/chat/modules/socket.jsm
@@ -79,17 +79,17 @@
 
 /*
  * To Do:
  *   Add a message queue to keep from flooding a server (just an array, just
  *     keep shifting the first element off and calling as setTimeout for the
  *     desired flood time?).
  */
 
-var EXPORTED_SYMBOLS = ["Socket"];
+const EXPORTED_SYMBOLS = ["Socket"];
 
 const {classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
 Cu.import("resource://gre/modules/Services.jsm");
 
 // Network errors see: netwerk/base/public/nsNetError.h
 const NS_ERROR_MODULE_NETWORK = 2152398848;
 const NS_ERROR_CONNECTION_REFUSED = NS_ERROR_MODULE_NETWORK + 13;
 const NS_ERROR_NET_TIMEOUT = NS_ERROR_MODULE_NETWORK + 14;

--- a/chat/protocols/xmpp/xmpp-authmechs.jsm
+++ b/chat/protocols/xmpp/xmpp-authmechs.jsm
@@ -38,17 +38,17 @@
 // This module exports XMPPAuthMechanisms, an object containing all
 // the supported SASL authentication mechanisms.
 // By default we currently support the PLAIN and the DIGEST-MD5 mechanisms.
 // As this is only used by XMPPSession, it may seem like an internal
 // detail of the XMPP implementation, but exporting it is valuable so that
 // add-ons can add support for more auth mechanisms easily by adding them
 // in XMPPAuthMechanisms without having to modify XMPPSession.
 
-var EXPORTED_SYMBOLS = ["XMPPAuthMechanisms"];
+const EXPORTED_SYMBOLS = ["XMPPAuthMechanisms"];
 
 const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
 
 Cu.import("resource:///modules/xmpp-xml.jsm");
 
 /* Handle PLAIN authorization mechanism */
 function PlainAuth(username, password, domain) {
   this._username = username;

--- a/chat/protocols/xmpp/xmpp-session.jsm
+++ b/chat/protocols/xmpp/xmpp-session.jsm
@@ -30,17 +30,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = ["XMPPSession", "XMPPDefaultResource"];
+const EXPORTED_SYMBOLS = ["XMPPSession", "XMPPDefaultResource"];
 
 const {interfaces: Ci, utils: Cu} = Components;
 
 Cu.import("resource:///modules/imXPCOMUtils.jsm");
 Cu.import("resource:///modules/socket.jsm");
 Cu.import("resource:///modules/xmpp-xml.jsm");
 Cu.import("resource:///modules/xmpp-authmechs.jsm");
 

--- a/chat/protocols/xmpp/xmpp-xml.jsm
+++ b/chat/protocols/xmpp/xmpp-xml.jsm
@@ -30,17 +30,17 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = ["Stanza", "XMPPParser"];
+const EXPORTED_SYMBOLS = ["Stanza", "XMPPParser"];
 
 const {classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
 
 const NS = {
   xml                       : "http://www.w3.org/XML/1998/namespace",
   xhtml                     : "http://www.w3.org/1999/xhtml",
   xhtml_im                  : "http://jabber.org/protocol/xhtml-im",
 

--- a/chat/protocols/xmpp/xmpp.jsm
+++ b/chat/protocols/xmpp/xmpp.jsm
@@ -30,20 +30,22 @@
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-var EXPORTED_SYMBOLS = ["XMPPConversationPrototype",
-                        "XMPPMUCConversationPrototype",
-                        "XMPPAccountBuddyPrototype",
-                        "XMPPAccountPrototype"];
+const EXPORTED_SYMBOLS = [
+  "XMPPConversationPrototype",
+  "XMPPMUCConversationPrototype",
+  "XMPPAccountBuddyPrototype",
+  "XMPPAccountPrototype"
+];
 
 const {classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
 
 Cu.import("resource:///modules/imServices.jsm");
 Cu.import("resource:///modules/imStatusUtils.jsm");
 Cu.import("resource:///modules/imXPCOMUtils.jsm");
 Cu.import("resource:///modules/jsProtoHelper.jsm");
 Cu.import("resource:///modules/socket.jsm");

--- a/im/modules/imWindows.jsm
+++ b/im/modules/imWindows.jsm
@@ -31,17 +31,17 @@
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
 const CONVERSATION_WINDOW_URI = "chrome://instantbird/content/instantbird.xul";
-var EXPORTED_SYMBOLS = ["Conversations"];
+const EXPORTED_SYMBOLS = ["Conversations"];
 
 Components.utils.import("resource:///modules/imServices.jsm");
 Components.utils.import("resource:///modules/ibInterruptions.jsm");
 
 var Conversations = {
   _unreadCount: 0,
   get unreadCount() this._unreadCount,
   set unreadCount(val) {