diff --git a/dom/base/Navigator.cpp b/dom/base/Navigator.cpp
index a74da5d17a3..13de83abef8 100644
--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -102,8 +102,7 @@ Navigator::Init()
 Navigator::Navigator(nsPIDOMWindow* aWindow)
   : mWindow(aWindow)
 {
-  NS_ASSERTION(aWindow->IsInnerWindow(),
-               "Navigator must get an inner window!");
+  MOZ_ASSERT(aWindow->IsInnerWindow(), "Navigator must get an inner window!");
   SetIsDOMBinding();
 }
 
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 55edf6b181b..a88cba24757 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -2871,6 +2871,8 @@ nsGlobalWindow::UpdateParentTarget()
 bool
 nsGlobalWindow::GetIsTabModalPromptAllowed()
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   bool allowTabModal = true;
   if (mDocShell) {
     nsCOMPtr<nsIContentViewer> cv;
@@ -2964,6 +2966,8 @@ nsGlobalWindow::PreHandleEvent(nsEventChainPreVisitor& aVisitor)
 bool
 nsGlobalWindow::ShouldPromptToBlockDialogs()
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   nsGlobalWindow *topWindow = GetScriptableTop();
   if (!topWindow) {
     NS_ASSERTION(!mDocShell, "ShouldPromptToBlockDialogs() called without a top window?");
@@ -3011,6 +3015,7 @@ nsGlobalWindow::AreDialogsEnabled()
 bool
 nsGlobalWindow::DialogsAreBeingAbused()
 {
+  MOZ_ASSERT(IsInnerWindow());
   NS_ASSERTION(GetScriptableTop() &&
                GetScriptableTop()->GetCurrentInnerWindowInternal() == this,
                "DialogsAreBeingAbused called with invalid window");
@@ -4590,7 +4595,7 @@ nsGlobalWindow::SetInnerHeight(int32_t aInnerHeight)
 nsIntSize
 nsGlobalWindow::GetOuterSize(ErrorResult& aError)
 {
-  FORWARD_TO_OUTER_OR_THROW(GetOuterSize, (aError), aError, nsIntSize(0, 0));
+  MOZ_ASSERT(IsOuterWindow());
 
   nsCOMPtr<nsIBaseWindow> treeOwnerAsWin = GetTreeOwnerWindow();
   if (!treeOwnerAsWin) {
@@ -4616,6 +4621,7 @@ nsGlobalWindow::GetOuterSize(ErrorResult& aError)
 int32_t
 nsGlobalWindow::GetOuterWidth(ErrorResult& aError)
 {
+  FORWARD_TO_OUTER_OR_THROW(GetOuterWidth, (aError), aError, 0);
   return GetOuterSize(aError).width;
 }
 
@@ -4631,6 +4637,7 @@ nsGlobalWindow::GetOuterWidth(int32_t* aOuterWidth)
 int32_t
 nsGlobalWindow::GetOuterHeight(ErrorResult& aError)
 {
+  FORWARD_TO_OUTER_OR_THROW(GetOuterHeight, (aError), aError, 0);
   return GetOuterSize(aError).height;
 }
 
@@ -4647,6 +4654,8 @@ void
 nsGlobalWindow::SetOuterSize(int32_t aLengthCSSPixels, bool aIsWidth,
                              ErrorResult& aError)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   /*
    * If caller is not chrome and the user has not explicitly exempted the site,
    * prevent setting window.outerWidth by exiting early
@@ -4748,6 +4757,8 @@ nsGlobalWindow::GetScreenX(int32_t* aScreenX)
 nsRect
 nsGlobalWindow::GetInnerScreenRect()
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   if (!mDocShell) {
     return nsRect();
   }
@@ -5138,6 +5149,8 @@ nsGlobalWindow::SetScreenY(int32_t aScreenY)
 void
 nsGlobalWindow::CheckSecurityWidthAndHeight(int32_t* aWidth, int32_t* aHeight)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
 #ifdef MOZ_XUL
   if (!nsContentUtils::IsCallerChrome()) {
     // if attempting to resize the window, hide any open popups
@@ -5165,6 +5178,8 @@ nsGlobalWindow::CheckSecurityWidthAndHeight(int32_t* aWidth, int32_t* aHeight)
 nsresult
 nsGlobalWindow::SetDocShellWidthAndHeight(int32_t aInnerWidth, int32_t aInnerHeight)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   NS_ENSURE_TRUE(mDocShell, NS_ERROR_FAILURE);
 
   nsCOMPtr<nsIDocShellTreeOwner> treeOwner;
@@ -5181,6 +5196,8 @@ nsGlobalWindow::SetDocShellWidthAndHeight(int32_t aInnerWidth, int32_t aInnerHei
 void
 nsGlobalWindow::SetCSSViewportWidthAndHeight(nscoord aInnerWidth, nscoord aInnerHeight)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   nsRefPtr<nsPresContext> presContext;
   mDocShell->GetPresContext(getter_AddRefs(presContext));
 
@@ -5196,6 +5213,8 @@ nsGlobalWindow::SetCSSViewportWidthAndHeight(nscoord aInnerWidth, nscoord aInner
 void
 nsGlobalWindow::CheckSecurityLeftAndTop(int32_t* aLeft, int32_t* aTop)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   // This one is harder. We have to get the screen size and window dimensions.
 
   // Check security state for use in determing window dimensions
@@ -5733,8 +5752,7 @@ nsGlobalWindow::Dump(const nsAString& aStr)
 void
 nsGlobalWindow::EnsureReflowFlushAndPaint()
 {
-  NS_ASSERTION(IsOuterWindow(), "EnsureReflowFlushAndPaint() must be called on"
-               "the outer window");
+  MOZ_ASSERT(IsOuterWindow());
   NS_ASSERTION(mDocShell, "EnsureReflowFlushAndPaint() called with no "
                "docshell!");
 
@@ -5865,6 +5883,8 @@ nsGlobalWindow::MakeScriptDialogTitle(nsAString &aOutTitle)
 bool
 nsGlobalWindow::CanMoveResizeWindows()
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   // When called from chrome, we can avoid the following checks.
   if (!nsContentUtils::IsCallerChrome()) {
     // Don't allow scripts to move or resize windows that were not opened by a
@@ -9190,6 +9210,8 @@ nsGlobalWindow::GetLocation(nsIDOMLocation ** aLocation)
 void
 nsGlobalWindow::ActivateOrDeactivate(bool aActivate)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   // Set / unset mIsActive on the top level window, which is used for the
   // :-moz-window-inactive pseudoclass, and its sheet (if any).
   nsCOMPtr<nsIWidget> mainWidget = GetMainWidget();
@@ -9249,6 +9271,8 @@ nsGlobalWindow::SetActive(bool aActive)
 
 void nsGlobalWindow::SetIsBackground(bool aIsBackground)
 {
+  MOZ_ASSERT(IsOuterWindow());
+
   bool resetTimers = (!aIsBackground && IsBackground());
   nsPIDOMWindow::SetIsBackground(aIsBackground);
   if (resetTimers) {
@@ -9554,6 +9578,8 @@ public:
                      nsGlobalWindow* aWindow)
     : mWindow(aWindow)
   {
+    MOZ_ASSERT(mWindow);
+    MOZ_ASSERT(mWindow->IsInnerWindow());
     mOldURL.Assign(aOldURL);
     mNewURL.Assign(aNewURL);
   }
@@ -9600,7 +9626,7 @@ nsresult
 nsGlobalWindow::FireHashchange(const nsAString &aOldURL,
                                const nsAString &aNewURL)
 {
-  NS_ENSURE_TRUE(IsInnerWindow(), NS_ERROR_FAILURE);
+  MOZ_ASSERT(IsInnerWindow());
 
   // Don't do anything if the window is frozen.
   if (IsFrozen())
@@ -9725,6 +9751,8 @@ static nsCanvasFrame* FindCanvasFrame(nsIFrame* aFrame)
 void
 nsGlobalWindow::UpdateCanvasFocus(bool aFocusChanged, nsIContent* aNewContent)
 {
+  MOZ_ASSERT(IsInnerWindow());
+
   // this is called from the inner window so use GetDocShell
   nsIDocShell* docShell = GetDocShell();
   if (!docShell)
@@ -10549,6 +10577,7 @@ nsGlobalWindow::ShowSlowScriptDialog()
 uint32_t
 nsGlobalWindow::FindInsertionIndex(IdleObserverHolder* aIdleObserver)
 {
+  MOZ_ASSERT(IsInnerWindow());
   MOZ_ASSERT(aIdleObserver, "Idle observer not instantiated.");
 
   uint32_t i = 0;
@@ -10755,6 +10784,7 @@ nsGlobalWindow::Observe(nsISupports* aSubject, const char* aTopic,
       mNotifyIdleObserversActiveOnThaw = true;
       mNotifyIdleObserversIdleOnThaw = false;
     } else if (IsCurrentInnerWindow()) {
+      MOZ_ASSERT(IsInnerWindow());
       ScheduleActiveTimerCallback();
     }
     return NS_OK;
@@ -11017,6 +11047,7 @@ nsGlobalWindow::GetParentInternal()
 void
 nsGlobalWindow::UnblockScriptedClosing()
 {
+  MOZ_ASSERT(IsOuterWindow());
   mBlockScriptedClosingFlag = false;
 }
 
@@ -11025,12 +11056,17 @@ class AutoUnblockScriptClosing
 private:
   nsRefPtr<nsGlobalWindow> mWin;
 public:
-  AutoUnblockScriptClosing(nsGlobalWindow *aWin) : mWin(aWin) {};
+  AutoUnblockScriptClosing(nsGlobalWindow* aWin)
+    : mWin(aWin)
+  {
+    MOZ_ASSERT(mWin);
+    MOZ_ASSERT(mWin->IsOuterWindow());
+  }
   ~AutoUnblockScriptClosing()
   {
     void (nsGlobalWindow::*run)() = &nsGlobalWindow::UnblockScriptedClosing;
     NS_DispatchToCurrentThread(NS_NewRunnableMethod(mWin, run));
-  };
+  }
 };
 
 nsresult
@@ -12534,6 +12570,8 @@ nsGlobalWindow::TimeoutSuspendCount()
 void
 nsGlobalWindow::EnableDeviceSensor(uint32_t aType)
 {
+  MOZ_ASSERT(IsInnerWindow());
+
   bool alreadyEnabled = false;
   for (uint32_t i = 0; i < mEnabledSensors.Length(); i++) {
     if (mEnabledSensors[i] == aType) {
@@ -12557,6 +12595,8 @@ nsGlobalWindow::EnableDeviceSensor(uint32_t aType)
 void
 nsGlobalWindow::DisableDeviceSensor(uint32_t aType)
 {
+  MOZ_ASSERT(IsInnerWindow());
+
   int32_t doomedElement = -1;
   int32_t listenerCount = 0;
   for (uint32_t i = 0; i < mEnabledSensors.Length(); i++) {
@@ -13085,6 +13125,8 @@ nsGlobalModalWindow::SetReturnValue(nsIVariant *aRetVal)
 void
 nsGlobalWindow::SetHasAudioAvailableEventListeners()
 {
+  MOZ_ASSERT(IsInnerWindow());
+
   if (mDoc) {
     mDoc->NotifyAudioAvailableListener();
   }
@@ -13094,6 +13136,8 @@ nsGlobalWindow::SetHasAudioAvailableEventListeners()
 void
 nsGlobalWindow::EnableNetworkEvent(uint32_t aType)
 {
+  MOZ_ASSERT(IsInnerWindow());
+
   nsCOMPtr<nsIPermissionManager> permMgr =
     do_GetService(NS_PERMISSIONMANAGER_CONTRACTID);
   if (!permMgr) {
@@ -13134,6 +13178,8 @@ nsGlobalWindow::EnableNetworkEvent(uint32_t aType)
 void
 nsGlobalWindow::DisableNetworkEvent(uint32_t aType)
 {
+  MOZ_ASSERT(IsInnerWindow());
+
   nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
   if (!os) {
     return;
diff --git a/dom/base/nsGlobalWindow.h b/dom/base/nsGlobalWindow.h
index ccd0d449405..fec72ace0d3 100644
--- a/dom/base/nsGlobalWindow.h
+++ b/dom/base/nsGlobalWindow.h
@@ -411,9 +411,12 @@ public:
 
   // nsPIDOMWindow
   virtual NS_HIDDEN_(nsPIDOMWindow*) GetPrivateRoot();
+
+  // Outer windows only.
   virtual NS_HIDDEN_(void) ActivateOrDeactivate(bool aActivate);
   virtual NS_HIDDEN_(void) SetActive(bool aActive);
   virtual NS_HIDDEN_(void) SetIsBackground(bool aIsBackground);
+
   virtual NS_HIDDEN_(void) SetChromeEventHandler(mozilla::dom::EventTarget* aChromeEventHandler);
 
   virtual NS_HIDDEN_(void) SetInitialPrincipalToSubject();
@@ -445,6 +448,7 @@ public:
   void DispatchDOMWindowCreated();
   virtual NS_HIDDEN_(void) SetOpenerWindow(nsIDOMWindow* aOpener,
                                            bool aOriginalOpener);
+
   // Outer windows only.
   virtual NS_HIDDEN_(void) EnsureSizeUpToDate();
 
@@ -520,7 +524,9 @@ public:
   // ShouldPromptToBlockDialogs is implemented in terms of
   // DialogsAreBeingAbused, and will get the scriptable top inner window
   // automatically.
+  // Outer windows only.
   bool ShouldPromptToBlockDialogs();
+  // Inner windows only.
   bool DialogsAreBeingAbused();
 
   // Ask the user if further dialogs should be blocked, if dialogs are currently
@@ -534,6 +540,7 @@ public:
   void DisableDialogs();
   bool AreDialogsEnabled();
 
+  // Inner windows only.
   virtual void SetHasAudioAvailableEventListeners();
 
   nsIScriptContext *GetContextInternal()
@@ -588,6 +595,7 @@ public:
   nsresult Observe(nsISupports* aSubject, const char* aTopic,
                    const PRUnichar* aData);
 
+  // Outer windows only.
   void UnblockScriptedClosing();
 
   static void Init();
@@ -616,6 +624,7 @@ public:
   virtual nsresult DispatchAsyncHashchange(nsIURI *aOldURI, nsIURI *aNewURI);
   virtual nsresult DispatchSyncPopState();
 
+  // Inner windows only.
   virtual void EnableDeviceSensor(uint32_t aType);
   virtual void DisableDeviceSensor(uint32_t aType);
 
@@ -623,6 +632,7 @@ public:
   virtual void DisableTimeChangeNotifications();
 
 #ifdef MOZ_B2G
+  // Inner windows only.
   virtual void EnableNetworkEvent(uint32_t aType);
   virtual void DisableNetworkEvent(uint32_t aType);
 #endif // MOZ_B2G
@@ -1136,6 +1146,7 @@ protected:
                            const nsAString &aPopupWindowFeatures);
   void FireOfflineStatusEvent();
 
+  // Inner windows only.
   nsresult ScheduleNextIdleObserverCallback();
   uint32_t GetFuzzTimeMS();
   nsresult ScheduleActiveTimerCallback();
@@ -1145,13 +1156,17 @@ protected:
                                       int32_t* aRemoveElementIndex);
   virtual nsresult UnregisterIdleObserver(nsIIdleObserver* aIdleObserverPtr);
 
+  // Inner windows only.
   nsresult FireHashchange(const nsAString &aOldURL, const nsAString &aNewURL);
 
   void FlushPendingNotifications(mozFlushType aType);
+
+  // Outer windows only.
   void EnsureReflowFlushAndPaint();
   void CheckSecurityWidthAndHeight(int32_t* width, int32_t* height);
   void CheckSecurityLeftAndTop(int32_t* left, int32_t* top);
 
+  // Outer windows only.
   // Arguments to this function should have values in app units
   void SetCSSViewportWidthAndHeight(nscoord width, nscoord height);
   // Arguments to this function should have values in device pixels
@@ -1161,10 +1176,9 @@ protected:
 
   static void MakeScriptDialogTitle(nsAString &aOutTitle);
 
+  // Outer windows only.
   bool CanMoveResizeWindows();
 
-  bool     GetBlurSuppression();
-
   // If aDoFlush is true, we'll flush our own layout; otherwise we'll try to
   // just flush our parent and only flush ourselves if we think we need to.
   mozilla::CSSIntPoint GetScrollXY(bool aDoFlush, mozilla::ErrorResult& aError);
@@ -1174,7 +1188,6 @@ protected:
 
   // Outer windows only.
   nsresult GetInnerSize(mozilla::CSSIntSize& aSize);
-
   nsIntSize GetOuterSize(mozilla::ErrorResult& aError);
   void SetOuterSize(int32_t aLengthCSSPixels, bool aIsWidth,
                     mozilla::ErrorResult& aError);
@@ -1187,6 +1200,7 @@ protected:
     return GetParentInternal() != nullptr;
   }
 
+  // Outer windows only.
   // If aLookForCallerOnJSStack is true, this method will look at the JS stack
   // to determine who the caller is.  If it's false, it'll use |this| as the
   // caller.
@@ -1231,6 +1245,7 @@ protected:
   virtual void GetKeyboardIndicators(bool* aShowAccelerators,
                                      bool* aShowFocusRings);
 
+  // Inner windows only.
   void UpdateCanvasFocus(bool aFocusChanged, nsIContent* aNewContent);
 
 public:
@@ -1247,6 +1262,7 @@ protected:
 
   virtual void UpdateParentTarget();
 
+  // Outer windows only.
   bool GetIsTabModalPromptAllowed();
 
   inline int32_t DOMMinTimeoutValue() const;
@@ -1398,7 +1414,7 @@ protected:
   nsRefPtr<nsDOMWindowUtils>    mWindowUtils;
   nsString                      mStatus;
   nsString                      mDefaultStatus;
-  nsGlobalWindowObserver*       mObserver;
+  nsGlobalWindowObserver*       mObserver; // Inner windows only.
   nsCOMPtr<nsIDOMCrypto>        mCrypto;
 
   nsCOMPtr<nsIDOMStorage>      mLocalStorage;
diff --git a/dom/base/nsPIDOMWindow.h b/dom/base/nsPIDOMWindow.h
index 151cab42175..723ea5ca0b0 100644
--- a/dom/base/nsPIDOMWindow.h
+++ b/dom/base/nsPIDOMWindow.h
@@ -70,39 +70,37 @@ public:
 
   virtual nsPIDOMWindow* GetPrivateRoot() = 0;
 
+  // Outer windows only.
   virtual void ActivateOrDeactivate(bool aActivate) = 0;
 
   // this is called GetTopWindowRoot to avoid conflicts with nsIDOMWindow::GetWindowRoot
   virtual already_AddRefed<nsPIWindowRoot> GetTopWindowRoot() = 0;
 
-  virtual void SetActive(bool aActive)
-  {
-    NS_PRECONDITION(IsOuterWindow(),
-                    "active state is only maintained on outer windows");
-    mIsActive = aActive;
-  }
-
+  // Inner windows only.
   virtual nsresult RegisterIdleObserver(nsIIdleObserver* aIdleObserver) = 0;
   virtual nsresult UnregisterIdleObserver(nsIIdleObserver* aIdleObserver) = 0;
 
+  // Outer windows only.
+  virtual void SetActive(bool aActive)
+  {
+    MOZ_ASSERT(IsOuterWindow());
+    mIsActive = aActive;
+  }
   bool IsActive()
   {
-    NS_PRECONDITION(IsOuterWindow(),
-                    "active state is only maintained on outer windows");
+    MOZ_ASSERT(IsOuterWindow());
     return mIsActive;
   }
 
+  // Outer windows only.
   virtual void SetIsBackground(bool aIsBackground)
   {
-    NS_PRECONDITION(IsOuterWindow(),
-                    "background state is only maintained on outer windows");
+    MOZ_ASSERT(IsOuterWindow());
     mIsBackground = aIsBackground;
   }
-
   bool IsBackground()
   {
-    NS_PRECONDITION(IsOuterWindow(),
-                    "background state is only maintained on outer windows");
+    MOZ_ASSERT(IsOuterWindow());
     return mIsBackground;
   }
 
@@ -566,12 +564,18 @@ public:
   virtual nsresult DispatchSyncPopState() = 0;
 
   /**
-   * Tell this window that it should listen for sensor changes of the given type.
+   * Tell this window that it should listen for sensor changes of the given
+   * type.
+   *
+   * Inner windows only.
    */
   virtual void EnableDeviceSensor(uint32_t aType) = 0;
 
   /**
-   * Tell this window that it should remove itself from sensor change notifications.
+   * Tell this window that it should remove itself from sensor change
+   * notifications.
+   *
+   * Inner windows only.
    */
   virtual void DisableDeviceSensor(uint32_t aType) = 0;
 
@@ -582,12 +586,16 @@ public:
   /**
    * Tell the window that it should start to listen to the network event of the
    * given aType.
+   *
+   * Inner windows only.
    */
   virtual void EnableNetworkEvent(uint32_t aType) = 0;
 
   /**
    * Tell the window that it should stop to listen to the network event of the
    * given aType.
+   *
+   * Inner windows only.
    */
   virtual void DisableNetworkEvent(uint32_t aType) = 0;
 #endif // MOZ_B2G