--- a/browser/base/content/browser-social.js
+++ b/browser/base/content/browser-social.js
@@ -532,17 +532,17 @@ SocialShare = {
     let provider = Social._getProviderFromOrigin(tt.triggerNode.getAttribute("origin"));
     tt.firstChild.setAttribute("value", provider.name);
     tt.lastChild.setAttribute("value", provider.origin);
   },
 
   populateProviderMenu: function() {
     if (!this.iframe)
       return;
-    let providers = [p for (p of Social.providers) if (p.shareURL)];
+    let providers = Social.providers.filter(p => p.shareURL);
     let hbox = document.getElementById("social-share-provider-buttons");
     // remove everything before the add-share-provider button (which should also
     // be lastChild if any share providers were added)
     let addButton = document.getElementById("add-share-provider");
     while (hbox.lastChild != addButton) {
       hbox.removeChild(hbox.lastChild);
     }
     let selectedProvider = this.getSelectedProvider();
@@ -971,17 +971,17 @@ SocialSidebar = {
   _provider: null,
   ensureProvider: function() {
     if (this._provider)
       return;
     // origin for sidebar is persisted, so get the previously selected sidebar
     // first, otherwise fallback to the first provider in the list
     let sbrowser = document.getElementById("social-sidebar-browser");
     let origin = sbrowser.getAttribute("origin");
-    let providers = [p for (p of Social.providers) if (p.sidebarURL)];
+    let providers = Social.providers.filter(p => p.sidebarURL);
     let provider;
     if (origin)
       provider = Social._getProviderFromOrigin(origin);
     if (!provider && providers.length > 0)
       provider = providers[0];
     if (provider)
       this.provider = provider;
   },
@@ -1088,17 +1088,17 @@ SocialSidebar = {
   populateProviderMenu: function(providerMenuSep) {
     let menu = providerMenuSep.parentNode;
     // selectable providers are inserted before the provider-menu seperator,
     // remove any menuitems in that area
     while (providerMenuSep.previousSibling.nodeName == "menuitem") {
       menu.removeChild(providerMenuSep.previousSibling);
     }
     // only show a selection in the sidebar header menu if there is more than one
-    let providers = [p for (p of Social.providers) if (p.sidebarURL)];
+    let providers = Social.providers.filter(p => p.sidebarURL);
     if (providers.length < 2 && menu.id != "viewSidebarMenu") {
       providerMenuSep.hidden = true;
       return;
     }
     let topSep = providerMenuSep.previousSibling;
     for (let provider of providers) {
       let menuitem = document.createElement("menuitem");
       menuitem.className = "menuitem-iconic social-provider-menuitem";
@@ -1148,17 +1148,19 @@ ToolbarHelper.prototype = {
   },
 
   // should be called on disable of a provider
   removeProviderButton: function(origin) {
     CustomizableUI.destroyWidget(this.idFromOrigin(origin));
   },
 
   clearPalette: function() {
-    [this.removeProviderButton(p.origin) for (p of Social.providers)];
+    for (let p of Social.providers) {
+      this.removeProviderButton(p.origin);
+    }
   },
 
   // should be called on enable of a provider
   populatePalette: function() {
     if (!Social.enabled) {
       this.clearPalette();
       return;
     }
@@ -1315,18 +1317,17 @@ var SocialMarksWidgetListener = {
 
 /**
  * SocialMarks
  *
  * Handles updates to toolbox and signals all buttons to update when necessary.
  */
 SocialMarks = {
   get nodes() {
-    let providers = [p for (p of Social.providers) if (p.markURL)];
-    for (let p of providers) {
+    for (let p of Social.providers.filter(p => p.markURL)) {
       let widgetId = SocialMarks._toolbarHelper.idFromOrigin(p.origin);
       let widget = CustomizableUI.getWidget(widgetId);
       if (!widget)
         continue;
       let node = widget.forWindow(window).node;
       if (node)
         yield node;
     }
@@ -1344,27 +1345,28 @@ SocialMarks = {
   },
 
   getProviders: function() {
     // only rely on providers that the user has placed in the UI somewhere. This
     // also means that populateToolbarPalette must be called prior to using this
     // method, otherwise you get a big fat zero. For our use case with context
     // menu's, this is ok.
     let tbh = this._toolbarHelper;
-    return [p for (p of Social.providers) if (p.markURL &&
-                                              document.getElementById(tbh.idFromOrigin(p.origin)))];
+    return Social.providers.filter(p => p.markURL &&
+                                        document.getElementById(tbh.idFromOrigin(p.origin)));
   },
 
   populateContextMenu: function() {
     // only show a selection if enabled and there is more than one
     let providers = this.getProviders();
 
     // remove all previous entries by class
-    let menus = [m for (m of document.getElementsByClassName("context-socialmarks"))];
-    [m.parentNode.removeChild(m) for (m of menus)];
+    for (let m of document.getElementsByClassName("context-socialmarks")) {
+      m.parentNode.removeChild(m);
+    }
 
     let contextMenus = [
       {
         type: "link",
         id: "context-marklinkMenu",
         label: "social.marklinkMenu.label"
       },
       {

--- a/browser/components/customizableui/content/jar.mn
+++ b/browser/components/customizableui/content/jar.mn
@@ -1,11 +1,11 @@
 # 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/.
 
 browser.jar:
   content/browser/customizableui/aboutCustomizing.xul
   content/browser/customizableui/panelUI.css
-* content/browser/customizableui/panelUI.js
+  content/browser/customizableui/panelUI.js
   content/browser/customizableui/panelUI.xml
   content/browser/customizableui/toolbar.xml
 

--- a/browser/components/customizableui/content/panelUI.js
+++ b/browser/components/customizableui/content/panelUI.js
@@ -5,16 +5,18 @@
 XPCOMUtils.defineLazyModuleGetter(this, "CustomizableUI",
                                   "resource:///modules/CustomizableUI.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ScrollbarSampler",
                                   "resource:///modules/ScrollbarSampler.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Promise",
                                   "resource://gre/modules/Promise.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ShortcutUtils",
                                   "resource://gre/modules/ShortcutUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "AppConstants",
+                                  "resource://gre/modules/AppConstants.jsm");
 
 /**
  * Maintains the state and dispatches events for the main menu panel.
  */
 
 const PanelUI = {
   /** Panel events that we listen for. **/
   get kEvents() {
@@ -483,31 +485,32 @@ const PanelUI = {
       }
       button.setAttribute("class", "subviewbutton");
       fragment.appendChild(button);
     }
     items.appendChild(fragment);
   },
 
   _updateQuitTooltip: function() {
-#ifndef XP_WIN
-#ifdef XP_MACOSX
-    let tooltipId = "quit-button.tooltiptext.mac";
-#else
-    let tooltipId = "quit-button.tooltiptext.linux2";
-#endif
+    if (AppConstants.platform == "win") {
+      return;
+    }
+
+    let tooltipId = AppConstants.platform == "macosx" ?
+                    "quit-button.tooltiptext.mac" :
+                    "quit-button.tooltiptext.linux2";
+
     let brands = Services.strings.createBundle("chrome://branding/locale/brand.properties");
     let stringArgs = [brands.GetStringFromName("brandShortName")];
 
     let key = document.getElementById("key_quitApplication");
     stringArgs.push(ShortcutUtils.prettifyShortcut(key));
     let tooltipString = CustomizableUI.getLocalizedProperty({x: tooltipId}, "x", stringArgs);
     let quitButton = document.getElementById("PanelUI-quit");
     quitButton.setAttribute("tooltiptext", tooltipString);
-#endif
   },
 
   _overlayScrollListenerBoundFn: null,
   _overlayScrollListener: function(aMQL) {
     ScrollbarSampler.resetSystemScrollbarWidth();
     this._scrollWidth = null;
   },
 };

--- a/browser/components/downloads/content/downloads.js
+++ b/browser/components/downloads/content/downloads.js
@@ -466,21 +466,17 @@ const DownloadsPanel = {
         DownloadsView.richListBox.firstChild) {
       DownloadsView.richListBox.focus();
       DownloadsView.richListBox.selectedItem = DownloadsView.richListBox.lastChild;
       aEvent.preventDefault();
       return;
     }
 
     let pasting = aEvent.keyCode == Ci.nsIDOMKeyEvent.DOM_VK_V &&
-#ifdef XP_MACOSX
-                  aEvent.metaKey;
-#else
-                  aEvent.ctrlKey;
-#endif
+                  aEvent.getModifierState("Accel");
 
     if (!pasting) {
       return;
     }
 
     DownloadsCommon.log("Received a paste event.");
 
     let trans = Cc["@mozilla.org/widget/transferable;1"]

--- a/browser/components/downloads/jar.mn
+++ b/browser/components/downloads/jar.mn
@@ -1,17 +1,17 @@
 # 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/.
 
 browser.jar:
 *       content/browser/downloads/download.xml           (content/download.xml)
         content/browser/downloads/download.css           (content/download.css)
         content/browser/downloads/downloads.css          (content/downloads.css)
-*       content/browser/downloads/downloads.js           (content/downloads.js)
+        content/browser/downloads/downloads.js           (content/downloads.js)
 *       content/browser/downloads/downloadsOverlay.xul   (content/downloadsOverlay.xul)
         content/browser/downloads/indicator.js           (content/indicator.js)
         content/browser/downloads/indicatorOverlay.xul   (content/indicatorOverlay.xul)
 *       content/browser/downloads/allDownloadsViewOverlay.xul (content/allDownloadsViewOverlay.xul)
         content/browser/downloads/allDownloadsViewOverlay.js  (content/allDownloadsViewOverlay.js)
         content/browser/downloads/allDownloadsViewOverlay.css (content/allDownloadsViewOverlay.css)
 *       content/browser/downloads/contentAreaDownloadsView.xul (content/contentAreaDownloadsView.xul)
         content/browser/downloads/contentAreaDownloadsView.js  (content/contentAreaDownloadsView.js)