--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -2683,17 +2683,17 @@ nsCSSFrameConstructor::ConstructRootFram
 
   // Bind the viewport frame to the root view
   nsView* rootView = mPresShell->GetViewManager()->GetRootView();
   viewportFrame->SetView(rootView);
 
   nsContainerFrame::SyncFrameViewProperties(mPresShell->GetPresContext(), viewportFrame,
                                             viewportPseudoStyle, rootView);
   nsContainerFrame::SyncWindowProperties(mPresShell->GetPresContext(), viewportFrame,
-                                         rootView);
+                                         rootView, nullptr, nsContainerFrame::SET_ASYNC);
 
   // Make it an absolute container for fixed-pos elements
   viewportFrame->AddStateBits(NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
   viewportFrame->MarkAsAbsoluteContainingBlock();
 
   return viewportFrame;
 }
 

--- a/layout/base/nsIPresShell.h
+++ b/layout/base/nsIPresShell.h
@@ -135,18 +135,18 @@ typedef struct CapturingContentInfo {
   bool mPointerLock;
   bool mRetargetToElement;
   bool mPreventDrag;
   mozilla::StaticRefPtr<nsIContent> mContent;
 } CapturingContentInfo;
 
 // d910f009-d209-74c1-6b04-30c83c051c78
 #define NS_IPRESSHELL_IID \
-  { 0xd910f009, 0xd209, 0x74c1, \
-    { 0x6b, 0x04, 0x30, 0xc8, 0x3c, 0x05, 0x1c, 0x78 } }
+  { 0x025264c6, 0x0b12, 0x4804, \
+    { 0xa3, 0x3e, 0xb7, 0x73, 0xf2, 0x19, 0x48, 0x90 } }
 
 // debug VerifyReflow flags
 #define VERIFY_REFLOW_ON                    0x01
 #define VERIFY_REFLOW_NOISY                 0x02
 #define VERIFY_REFLOW_ALL                   0x04
 #define VERIFY_REFLOW_DUMP_COMMANDS         0x08
 #define VERIFY_REFLOW_NOISY_RC              0x10
 #define VERIFY_REFLOW_REALLY_NOISY_RC       0x20
@@ -1656,16 +1656,18 @@ public:
 
   void SetNeverPainting(bool aNeverPainting) {
     mIsNeverPainting = aNeverPainting;
   }
 
   bool HasPendingReflow() const
     { return mReflowScheduled || mReflowContinueTimer; }
 
+  void SyncWindowProperties(nsView* aView);
+
 protected:
   friend class nsRefreshDriver;
 
   // IMPORTANT: The ownership implicit in the following member variables
   // has been explicitly checked.  If you add any members to this class,
   // please make the ownership explicit (pinkerton, scc).
 
   // These are the same Document and PresContext owned by the DocViewer.

--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -9240,17 +9240,18 @@ PresShell::DoReflow(nsIFrame* target, bo
   // Always use boundsRelativeToTarget here, not desiredSize.GetVisualOverflowArea(),
   // because for root frames (where they could be different, since root frames
   // are allowed to have overflow) the root view bounds need to match the
   // viewport bounds; the view manager "window dimensions" code depends on it.
   nsContainerFrame::SyncFrameViewAfterReflow(mPresContext, target,
                                              target->GetView(),
                                              boundsRelativeToTarget);
   nsContainerFrame::SyncWindowProperties(mPresContext, target,
-                                         target->GetView(), &rcx);
+                                         target->GetView(), &rcx,
+                                         nsContainerFrame::SET_ASYNC);
 
   target->DidReflow(mPresContext, nullptr, nsDidReflowStatus::FINISHED);
   if (target == rootFrame && size.BSize(wm) == NS_UNCONSTRAINEDSIZE) {
     mPresContext->SetVisibleArea(boundsRelativeToTarget);
   }
 
 #ifdef DEBUG
   mCurrentReflowRoot = nullptr;
@@ -11076,8 +11077,18 @@ void
 PresShell::ResumePainting()
 {
   if (GetPresContext()->RefreshDriver()->PresContext() != GetPresContext())
     return;
 
   mPaintingIsFrozen = false;
   GetPresContext()->RefreshDriver()->Thaw();
 }
+
+void
+nsIPresShell::SyncWindowProperties(nsView* aView)
+{
+  nsIFrame* frame = aView->GetFrame();
+  if (frame && mPresContext) {
+    nsRenderingContext rcx(CreateReferenceRenderingContext());
+    nsContainerFrame::SyncWindowProperties(mPresContext, frame, aView, &rcx, 0);
+  }
+}

--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -604,24 +604,25 @@ IsTopLevelWidget(nsIWidget* aWidget)
          windowType == eWindowType_dialog ||
          windowType == eWindowType_sheet;
   // popups aren't toplevel so they're not handled here
 }
 
 void
 nsContainerFrame::SyncWindowProperties(nsPresContext*       aPresContext,
                                        nsIFrame*            aFrame,
-                                       nsView*             aView,
-                                       nsRenderingContext*  aRC)
+                                       nsView*              aView,
+                                       nsRenderingContext*  aRC,
+                                       uint32_t             aFlags)
 {
 #ifdef MOZ_XUL
   if (!aView || !nsCSSRendering::IsCanvasFrame(aFrame) || !aView->HasWidget())
     return;
 
-  nsIWidget* windowWidget = GetPresContextContainerWidget(aPresContext);
+  nsCOMPtr<nsIWidget> windowWidget = GetPresContextContainerWidget(aPresContext);
   if (!windowWidget || !IsTopLevelWidget(windowWidget))
     return;
 
   nsViewManager* vm = aView->GetViewManager();
   nsView* rootView = vm->GetRootView();
 
   if (aView != rootView)
     return;
@@ -645,24 +646,37 @@ nsContainerFrame::SyncWindowProperties(n
     // even if the HTML doesn't have a background-color set.
     return;
   }
 
   nsIFrame *rootFrame = aPresContext->PresShell()->FrameConstructor()->GetRootElementStyleFrame();
   if (!rootFrame)
     return;
 
+  if (aFlags & SET_ASYNC) {
+    aView->SetNeedsWindowPropertiesSync();
+    return;
+  }
+
+  nsRefPtr<nsPresContext> kungFuDeathGrip(aPresContext);
+  nsWeakFrame weak(rootFrame);
+
   nsTransparencyMode mode = nsLayoutUtils::GetFrameTransparency(aFrame, rootFrame);
-  nsIWidget* viewWidget = aView->GetWidget();
+  int32_t shadow = rootFrame->StyleUIReset()->mWindowShadow;
+  nsCOMPtr<nsIWidget> viewWidget = aView->GetWidget();
   viewWidget->SetTransparencyMode(mode);
-  windowWidget->SetWindowShadowStyle(rootFrame->StyleUIReset()->mWindowShadow);
+  windowWidget->SetWindowShadowStyle(shadow);
 
   if (!aRC)
     return;
-  
+
+  if (!weak.IsAlive()) {
+    return;
+  }
+
   nsBoxLayoutState aState(aPresContext, aRC);
   nsSize minSize = rootFrame->GetMinSize(aState);
   nsSize maxSize = rootFrame->GetMaxSize(aState);
 
   SetSizeConstraints(aPresContext, windowWidget, minSize, maxSize);
 #endif
 }
 

--- a/layout/generic/nsContainerFrame.h
+++ b/layout/generic/nsContainerFrame.h
@@ -175,20 +175,26 @@ public:
   static void SyncFrameViewAfterReflow(nsPresContext* aPresContext,
                                        nsIFrame*       aFrame,
                                        nsView*        aView,
                                        const nsRect&   aVisualOverflowArea,
                                        uint32_t        aFlags = 0);
 
   // Syncs properties to the top level view and window, like transparency and
   // shadow.
+  // The SET_ASYNC indicates that the actual nsIWidget calls to sync the window
+  // properties should be done async.
+  enum {
+    SET_ASYNC = 0x01,
+  };
   static void SyncWindowProperties(nsPresContext*       aPresContext,
                                    nsIFrame*            aFrame,
-                                   nsView*             aView,
-                                   nsRenderingContext*  aRC = nullptr);
+                                   nsView*              aView,
+                                   nsRenderingContext*  aRC,
+                                   uint32_t             aFlags);
 
   // Sets the view's attributes from the frame style.
   // - visibility
   // - clip
   // Call this when one of these styles changes or when the view has just
   // been created.
   // @param aStyleContext can be null, in which case the frame's style context is used
   static void SyncFrameViewProperties(nsPresContext*  aPresContext,

--- a/view/nsView.cpp
+++ b/view/nsView.cpp
@@ -668,16 +668,26 @@ nsView::InitializeWindow(bool aEnableDra
 
   //make sure visibility state is accurate
 
   if (aResetVisibility) {
     SetVisibility(GetVisibility());
   }
 }
 
+void
+nsView::SetNeedsWindowPropertiesSync()
+{
+  mNeedsWindowPropertiesSync = true;
+  if (mViewManager) {
+    mViewManager->PostPendingUpdate();
+  }
+}
+
+
 // Attach to a top level widget and start receiving mirrored events.
 nsresult nsView::AttachToTopLevelWidget(nsIWidget* aWidget)
 {
   NS_PRECONDITION(nullptr != aWidget, "null widget ptr");
   /// XXXjimm This is a temporary workaround to an issue w/document
   // viewer (bug 513162).
   nsIWidgetListener* listener = aWidget->GetAttachedWidgetListener();
   if (listener) {

--- a/view/nsView.h
+++ b/view/nsView.h
@@ -285,16 +285,18 @@ public:
    * Returns true if the view has a widget associated with it.
    */
   bool HasWidget() const { return mWindow != nullptr; }
   
   void SetForcedRepaint(bool aForceRepaint) { 
     mForcedRepaint = aForceRepaint; 
   }
 
+  void SetNeedsWindowPropertiesSync();
+
   /**
    * Make aWidget direct its events to this view.
    * The caller must call DetachWidgetEventHandler before this view
    * is destroyed.
    */
   void AttachWidgetEventHandler(nsIWidget* aWidget);
   /**
    * Stop aWidget directing its events to this view.
@@ -458,11 +460,12 @@ private:
   nscoord           mPosX, mPosY;
   // relative to parent, but in our appunits
   nsRect            mDimBounds;
   // in our appunits
   nsPoint           mViewToWidgetOffset;
   uint32_t          mVFlags;
   bool              mWidgetIsTopLevel;
   bool              mForcedRepaint;
+  bool              mNeedsWindowPropertiesSync;
 };
 
 #endif

--- a/view/nsViewManager.cpp
+++ b/view/nsViewManager.cpp
@@ -363,16 +363,27 @@ nsViewManager::ProcessPendingUpdatesForV
   }
 
   nsCOMPtr<nsIPresShell> rootShell(mPresShell);
   nsTArray<nsCOMPtr<nsIWidget> > widgets;
   aView->GetViewManager()->ProcessPendingUpdatesRecurse(aView, widgets);
   for (uint32_t i = 0; i < widgets.Length(); ++i) {
     nsView* view = nsView::GetViewFor(widgets[i]);
     if (view) {
+      if (view->mNeedsWindowPropertiesSync) {
+        view->mNeedsWindowPropertiesSync = false;
+        if (nsViewManager* vm = view->GetViewManager()) {
+          if (nsIPresShell* ps = vm->GetPresShell()) {
+            ps->SyncWindowProperties(view);
+          }
+        }
+      }
+    }
+    view = nsView::GetViewFor(widgets[i]);
+    if (view) {
       view->ResetWidgetBounds(false, true);
     }
   }
   if (rootShell->GetViewManager() != this) {
     return; // 'this' might have been destroyed
   }
   if (aFlushDirtyRegion) {
     profiler_tracing("Paint", "DisplayList", TRACING_INTERVAL_START);