--- a/layout/forms/nsListControlFrame.cpp
+++ b/layout/forms/nsListControlFrame.cpp
@@ -136,18 +136,17 @@ nsListControlFrame::DestroyFrom(nsIFrame
                                       mEventListener, false);
   mContent->RemoveSystemEventListener(NS_LITERAL_STRING("mousedown"),
                                       mEventListener, false);
   mContent->RemoveSystemEventListener(NS_LITERAL_STRING("mouseup"),
                                       mEventListener, false);
   mContent->RemoveSystemEventListener(NS_LITERAL_STRING("mousemove"),
                                       mEventListener, false);
 
-  if (XRE_IsContentProcess() &&
-      Preferences::GetBool("browser.tabs.remote.desktopbehavior", false)) {
+  if (Preferences::GetBool("browser.tabs.remote.desktopbehavior", false)) {
     nsContentUtils::AddScriptRunner(
       new AsyncEventDispatcher(mContent,
                                NS_LITERAL_STRING("mozhidedropdown"), true,
                                true));
   }
 
   nsFormControlFrame::RegUnRegAccessKey(static_cast<nsIFrame*>(this), false);
   nsHTMLScrollFrame::DestroyFrom(aDestructRoot);
@@ -1774,18 +1773,20 @@ nsListControlFrame::GetIndexFromDOMEvent
   }
 
   return NS_ERROR_FAILURE;
 }
 
 static bool
 FireShowDropDownEvent(nsIContent* aContent, bool show)
 {
-  if (XRE_IsContentProcess() &&
-      Preferences::GetBool("browser.tabs.remote.desktopbehavior", false)) {
+  if ((XRE_IsContentProcess() &&
+      Preferences::GetBool("browser.tabs.remote.desktopbehavior", false)) ||
+      Preferences::GetBool("dom.select_popup_in_parent.enabled"))
+  {
     nsContentUtils::DispatchChromeEvent(aContent->OwnerDoc(), aContent,
                                         show ? NS_LITERAL_STRING("mozshowdropdown") :
                                                NS_LITERAL_STRING("mozhidedropdown"),
                                         true, false);
     return true;
   }
 
   return false;

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -14,16 +14,17 @@
 /*
  * SYNTAX HINTS:
  *
  *  - Dashes are delimiters; use underscores instead.
  *  - The first character after a period must be alphabetic.
  *  - Computed values (e.g. 50 * 1024) don't work.
  */
 
+pref("dom.select_popup_in_parent.enabled", false);
 pref("keyword.enabled", false);
 pref("general.useragent.locale", "chrome://global/locale/intl.properties");
 pref("general.useragent.compatMode.firefox", false);
 
 // This pref exists only for testing purposes. In order to disable all
 // overrides by default, don't initialize UserAgentOverrides.jsm.
 pref("general.useragent.site_specific_overrides", true);
 

--- a/toolkit/content/browser-content.js
+++ b/toolkit/content/browser-content.js
@@ -10,16 +10,18 @@ var Cr = Components.results;
 
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "ReaderMode",
   "resource://gre/modules/ReaderMode.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "BrowserUtils",
   "resource://gre/modules/BrowserUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "SelectContentHelper",
+                                  "resource://gre/modules/SelectContentHelper.jsm");
 
 var global = this;
 
 
 // Lazily load the finder code
 addMessageListener("Finder:Initialize", function () {
   let {RemoteFinderListener} = Cu.import("resource://gre/modules/RemoteFinder.jsm", {});
   new RemoteFinderListener(global);
@@ -1663,8 +1665,17 @@ let DateTimePickerListener = {
       }
       default:
         break;
     }
   },
 }
 
 DateTimePickerListener.init();
+
+addEventListener("mozshowdropdown", event => {
+  if (!event.isTrusted)
+    return;
+
+  if (!SelectContentHelper.open) {
+    new SelectContentHelper(event.target, this);
+  }
+});

--- a/toolkit/content/jar.mn
+++ b/toolkit/content/jar.mn
@@ -56,17 +56,16 @@ toolkit.jar:
    content/global/filepicker.properties
    content/global/globalOverlay.js
    content/global/mozilla.xhtml
    content/global/process-content.js
    content/global/resetProfile.css
    content/global/resetProfile.js
    content/global/resetProfile.xul
    content/global/resetProfileProgress.xul
-   content/global/select-child.js
    content/global/TopLevelVideoDocument.js
    content/global/treeUtils.js
    content/global/viewZoomOverlay.js
    content/global/bindings/autocomplete.xml    (widgets/autocomplete.xml)
    content/global/bindings/browser.xml         (widgets/browser.xml)
    content/global/bindings/button.xml          (widgets/button.xml)
    content/global/bindings/checkbox.xml        (widgets/checkbox.xml)
    content/global/bindings/colorpicker.xml     (widgets/colorpicker.xml)
@@ -108,9 +107,9 @@ toolkit.jar:
    content/global/bindings/videocontrols.css   (widgets/videocontrols.css)
 *  content/global/bindings/wizard.xml          (widgets/wizard.xml)
 #ifdef XP_MACOSX
    content/global/macWindowMenu.js
 #endif
    content/global/svg/svgBindings.xml          (/layout/svg/resources/content/svgBindings.xml)
    content/global/gmp-sources/eme-adobe.json   (gmp-sources/eme-adobe.json)
    content/global/gmp-sources/openh264.json    (gmp-sources/openh264.json)
-   content/global/gmp-sources/widevinecdm.json (gmp-sources/widevinecdm.json)
\ No newline at end of file
+   content/global/gmp-sources/widevinecdm.json (gmp-sources/widevinecdm.json)

deleted file mode 100644
--- a/toolkit/content/select-child.js
+++ /dev/null
@@ -1,17 +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/. */
-
-Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
-
-XPCOMUtils.defineLazyModuleGetter(this, "SelectContentHelper",
-                                  "resource://gre/modules/SelectContentHelper.jsm");
-
-addEventListener("mozshowdropdown", event => {
-  if (!event.isTrusted)
-    return;
-
-  if (!SelectContentHelper.open) {
-    new SelectContentHelper(event.target, this);
-  }
-});

--- a/toolkit/content/widgets/browser.xml
+++ b/toolkit/content/widgets/browser.xml
@@ -917,16 +917,22 @@
           }
 
           if (this.messageManager) {
             this.messageManager.addMessageListener("PopupBlocking:UpdateBlockedPopups", this);
             this.messageManager.addMessageListener("Autoscroll:Start", this);
             this.messageManager.addMessageListener("Autoscroll:Cancel", this);
             this.messageManager.addMessageListener("AudioPlayback:Start", this);
             this.messageManager.addMessageListener("AudioPlayback:Stop", this);
+
+            if (this.hasAttribute("selectmenulist")) {
+              this.messageManager.addMessageListener("Forms:ShowDropDown", this);
+              this.messageManager.addMessageListener("Forms:HideDropDown", this);
+            }
+
           }
         ]]>
       </constructor>
 
       <destructor>
         <![CDATA[
           this.destroy();
         ]]>
@@ -935,16 +941,21 @@
       <!-- This is necessary because the destructor doesn't always get called when
            we are removed from a tabbrowser. This will be explicitly called by tabbrowser.
 
            Note: this function is overriden in remote-browser.xml, so any clean-up that
            also applies to browser.isRemoteBrowser = true must be duplicated there. -->
       <method name="destroy">
         <body>
           <![CDATA[
+          // Make sure that any open select is closed.
+          if (this._selectParentHelper) {
+            let menulist = document.getElementById(this.getAttribute("selectmenulist"));
+            this._selectParentHelper.hide(menulist, this);
+          }
           if (this.mDestroyed)
             return;
           this.mDestroyed = true;
 
           if (this.docShell && this.webNavigation.sessionHistory) {
             var os = Components.classes["@mozilla.org/observer-service;1"]
                                .getService(Components.interfaces.nsIObserverService);
             try {
@@ -1003,16 +1014,38 @@
               this._autoScrollPopup.hidePopup();
               break;
             case "AudioPlayback:Start":
               this.audioPlaybackStarted();
               break;
             case "AudioPlayback:Stop":
               this.audioPlaybackStopped();
               break;
+              
+            case "Forms:ShowDropDown": {
+              if (!this._selectParentHelper) {
+                this._selectParentHelper =
+                  Cu.import("resource://gre/modules/SelectParentHelper.jsm", {}).SelectParentHelper;
+              }
+
+              let menulist = document.getElementById(this.getAttribute("selectmenulist"));
+              menulist.menupopup.style.direction = data.direction;
+              this._selectParentHelper.populate(menulist, data.options, data.selectedIndex, this._fullZoom);
+              this._selectParentHelper.open(this, menulist, data.rect);
+              break;
+            }
+
+            case "Forms:HideDropDown": {
+              if (this._selectParentHelper) {
+                let menulist = document.getElementById(this.getAttribute("selectmenulist"));
+                this._selectParentHelper.hide(menulist, this);
+              }
+              break;
+            }
+
           }
           return undefined;
         ]]></body>
       </method>
 
       <method name="receiveMessage">
         <parameter name="aMessage"/>
         <body><![CDATA[

--- a/toolkit/content/widgets/remote-browser.xml
+++ b/toolkit/content/widgets/remote-browser.xml
@@ -384,17 +384,16 @@
           this.messageManager.addMessageListener("DOMFullscreen:RequestExit", this);
           this.messageManager.addMessageListener("DOMFullscreen:RequestRollback", this);
           this.messageManager.addMessageListener("MozApplicationManifest", this);
           this.messageManager.loadFrameScript("chrome://global/content/browser-child.js", true);
 
           if (this.hasAttribute("selectmenulist")) {
             this.messageManager.addMessageListener("Forms:ShowDropDown", this);
             this.messageManager.addMessageListener("Forms:HideDropDown", this);
-            this.messageManager.loadFrameScript("chrome://global/content/select-child.js", true);
           }
 
           if (!this.hasAttribute("disablehistory")) {
             Services.obs.addObserver(this, "browser:purge-session-history", true);
           }
 
           let jsm = "resource://gre/modules/RemoteController.jsm";
           let RemoteController = Components.utils.import(jsm, {}).RemoteController;
@@ -456,29 +455,16 @@
               break;
             case "ImageDocumentLoaded":
               this._imageDocument = {
                 width: data.width,
                 height: data.height
               };
               break;
 
-            case "Forms:ShowDropDown": {
-              if (!this._selectParentHelper) {
-                this._selectParentHelper =
-                  Cu.import("resource://gre/modules/SelectParentHelper.jsm", {}).SelectParentHelper;
-              }
-
-              let menulist = document.getElementById(this.getAttribute("selectmenulist"));
-              menulist.menupopup.style.direction = data.direction;
-              this._selectParentHelper.populate(menulist, data.options, data.selectedIndex, this._fullZoom);
-              this._selectParentHelper.open(this, menulist, data.rect);
-              break;
-            }
-
             case "FullZoomChange": {
               this._fullZoom = data.value;
               let event = document.createEvent("Events");
               event.initEvent("FullZoomChange", true, false);
               this.dispatchEvent(event);
               break;
             }
 
@@ -492,24 +478,16 @@
 
             case "ZoomChangeUsingMouseWheel": {
               let event = document.createEvent("Events");
               event.initEvent("ZoomChangeUsingMouseWheel", true, false);
               this.dispatchEvent(event);
               break;
             }
 
-            case "Forms:HideDropDown": {
-              if (this._selectParentHelper) {
-                let menulist = document.getElementById(this.getAttribute("selectmenulist"));
-                this._selectParentHelper.hide(menulist, this);
-              }
-              break;
-            }
-
             case "DOMFullscreen:RequestExit": {
               let windowUtils = window.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
                                       .getInterface(Components.interfaces.nsIDOMWindowUtils);
               windowUtils.exitFullscreen();
               break;
             }
 
             case "DOMFullscreen:RequestRollback": {