--- a/b2g/app/b2g.js
+++ b/b2g/app/b2g.js
@@ -679,19 +679,16 @@ pref("dom.ipc.reuse_parent_app", false);
 // When a process receives a system message, we hold a CPU wake lock on its
 // behalf for this many seconds, or until it handles the system message,
 // whichever comes first.
 pref("dom.ipc.systemMessageCPULockTimeoutSec", 30);
 
 // Ignore the "dialog=1" feature in window.open.
 pref("dom.disable_window_open_dialog_feature", true);
 
-// Enable before keyboard events and after keyboard events.
-pref("dom.beforeAfterKeyboardEvent.enabled", true);
-
 // Screen reader support
 pref("accessibility.accessfu.activate", 2);
 pref("accessibility.accessfu.quicknav_modes", "Link,Heading,FormElement,Landmark,ListItem");
 // Active quicknav mode, index value of list from quicknav_modes
 pref("accessibility.accessfu.quicknav_index", 0);
 // Setting for an utterance order (0 - description first, 1 - description last).
 pref("accessibility.accessfu.utterance", 1);
 // Whether to skip images with empty alt text

--- a/layout/base/PresShell.cpp
+++ b/layout/base/PresShell.cpp
@@ -739,17 +739,16 @@ nsIPresShell::FrameSelection()
 //----------------------------------------------------------------------
 
 static bool sSynthMouseMove = true;
 static uint32_t sNextPresShellId;
 static bool sPointerEventEnabled = true;
 static bool sPointerEventImplicitCapture = false;
 static bool sAccessibleCaretEnabled = false;
 static bool sAccessibleCaretOnTouch = false;
-static bool sBeforeAfterKeyboardEventEnabled = false;
 
 /* static */ bool
 PresShell::AccessibleCaretEnabled(nsIDocShell* aDocShell)
 {
   static bool initialized = false;
   if (!initialized) {
     Preferences::AddBoolVarCache(&sAccessibleCaretEnabled, "layout.accessiblecaret.enabled");
     Preferences::AddBoolVarCache(&sAccessibleCaretOnTouch, "layout.accessiblecaret.enabled_on_touch");
@@ -764,28 +763,16 @@ PresShell::AccessibleCaretEnabled(nsIDoc
   if (sAccessibleCaretOnTouch && dom::TouchEvent::PrefEnabled(aDocShell)) {
     return true;
   }
   // Otherwise, disabled.
   return false;
 }
 
 /* static */ bool
-PresShell::BeforeAfterKeyboardEventEnabled()
-{
-  static bool sInitialized = false;
-  if (!sInitialized) {
-    Preferences::AddBoolVarCache(&sBeforeAfterKeyboardEventEnabled,
-      "dom.beforeAfterKeyboardEvent.enabled");
-    sInitialized = true;
-  }
-  return sBeforeAfterKeyboardEventEnabled;
-}
-
-/* static */ bool
 PresShell::IsTargetIframe(nsINode* aTarget)
 {
   return aTarget && aTarget->IsHTMLElement(nsGkAtoms::iframe);
 }
 
 PresShell::PresShell()
   : mMouseLocation(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE)
 {
@@ -7036,65 +7023,16 @@ public:
 
 private:
   int32_t mPointerId;
   uint16_t mPointerType;
   bool mIsPrimary;
   bool mIsSet;
 };
 
-static bool
-CheckPermissionForBeforeAfterKeyboardEvent(Element* aElement)
-{
-  // An element which is chrome-privileged should be able to handle before
-  // events and after events.
-  nsIPrincipal* principal = aElement->NodePrincipal();
-  if (nsContentUtils::IsSystemPrincipal(principal)) {
-    return true;
-  }
-
-  // An element which has "before-after-keyboard-event" permission should be
-  // able to handle before events and after events.
-  nsCOMPtr<nsIPermissionManager> permMgr = services::GetPermissionManager();
-  uint32_t permission = nsIPermissionManager::DENY_ACTION;
-  if (permMgr) {
-    permMgr->TestPermissionFromPrincipal(principal, "before-after-keyboard-event", &permission);
-    if (permission == nsIPermissionManager::ALLOW_ACTION) {
-      return true;
-    }
-  }
-
-  return false;
-}
-
-static void
-BuildTargetChainForBeforeAfterKeyboardEvent(nsINode* aTarget,
-                                            nsTArray<nsCOMPtr<Element> >& aChain,
-                                            bool aTargetIsIframe)
-{
-  Element* frameElement;
-  // If event target is not an iframe, skip the event target and get its
-  // parent frame.
-  if (aTargetIsIframe) {
-    frameElement = aTarget->AsElement();
-  } else {
-    nsPIDOMWindowOuter* window = aTarget->OwnerDoc()->GetWindow();
-    frameElement = window ? window->GetFrameElementInternal() : nullptr;
-  }
-
-  // Check permission for all ancestors and add them into the target chain.
-  while (frameElement) {
-    if (CheckPermissionForBeforeAfterKeyboardEvent(frameElement)) {
-      aChain.AppendElement(frameElement);
-    }
-    nsPIDOMWindowOuter* window = frameElement->OwnerDoc()->GetWindow();
-    frameElement = window ? window->GetFrameElementInternal() : nullptr;
-  }
-}
-
 bool
 PresShell::CanDispatchEvent(const WidgetGUIEvent* aEvent) const
 {
   bool rv =
     mPresContext && !mHaveShutDown && nsContentUtils::IsSafeToRunScript();
   if (aEvent) {
     rv &= (aEvent && aEvent->mWidget && !aEvent->mWidget->Destroyed());
   }

--- a/layout/base/PresShell.h
+++ b/layout/base/PresShell.h
@@ -86,19 +86,16 @@ public:
 
   NS_DECL_AND_IMPL_ZEROING_OPERATOR_NEW
 
   // nsISupports
   NS_DECL_ISUPPORTS
 
   static bool AccessibleCaretEnabled(nsIDocShell* aDocShell);
 
-  // BeforeAfterKeyboardEvent preference
-  static bool BeforeAfterKeyboardEventEnabled();
-
   static bool IsTargetIframe(nsINode* aTarget);
 
   void Init(nsIDocument* aDocument, nsPresContext* aPresContext,
             nsViewManager* aViewManager, mozilla::StyleSetHandle aStyleSet);
   virtual void Destroy() override;
 
   virtual void UpdatePreferenceStyles() override;
 

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -5246,19 +5246,16 @@ pref("dom.caches.enabled", true);
 // supported will be disabled. This threshold can be adjusted to suit other
 // platforms; and set to 0 to disable the low-memory check altogether.
 pref("camera.control.low_memory_thresholdMB", 404);
 #endif
 
 // UDPSocket API
 pref("dom.udpsocket.enabled", false);
 
-// Disable before keyboard events and after keyboard events by default.
-pref("dom.beforeAfterKeyboardEvent.enabled", false);
-
 // Presentation API
 pref("dom.presentation.enabled", false);
 pref("dom.presentation.controller.enabled", false);
 pref("dom.presentation.receiver.enabled", false);
 
 // Presentation Device
 pref("dom.presentation.tcp_server.debug", false);
 pref("dom.presentation.discovery.enabled", false);

--- a/testing/mochitest/manifest.webapp
+++ b/testing/mochitest/manifest.webapp
@@ -21,17 +21,16 @@
     "camera":{},
     "geolocation":{},
     "wifi-manage":{},
     "desktop-notification":{},
     "idle":{},
     "network-events":{},
     "audio-channel-content":{},
     "audio-channel-alarm":{},
-    "before-after-keyboard-event":{}
   },
   "locales": {
     "en-US": {
       "name": "Mochitest",
       "description": "Mochitests"
     }
   },
   "default_locale": "en-US"