diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index 0eab1ed872f..d5b7a969ffe 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -2131,7 +2131,14 @@ nsHTMLDocument::Close()
     // handler of the frameset fires before the frames get reflowed
     // and loaded.  That is the long explanation for why we need this
     // one line of code here!
-    FlushPendingNotifications(Flush_Layout);
+    // XXXbz as far as I can tell this may not be needed anymore; all
+    // the testcases in bug 57636 pass without this line...  Leaving
+    // it be for now, though.  In any case, there's no reason to do
+    // this if we have no presshell, since in that case none of the
+    // above about reusing frames applies.
+    if (GetNumberOfShells() != 0) {
+      FlushPendingNotifications(Flush_Layout);
+    }
 
     // Remove the wyciwyg channel request from the document load group
     // that we added in OpenCommon().  If all other requests between
diff --git a/mozilla/layout/base/nsCSSFrameConstructor.cpp b/mozilla/layout/base/nsCSSFrameConstructor.cpp
index 567593189ca..c21177fd640 100644
--- a/mozilla/layout/base/nsCSSFrameConstructor.cpp
+++ b/mozilla/layout/base/nsCSSFrameConstructor.cpp
@@ -1,4 +1,4 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+ /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 // vim:cindent:ts=2:et:sw=2:
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
@@ -8395,6 +8395,11 @@ nsCSSFrameConstructor::ContentAppended(nsIContent*     aContainer,
 
   parentFrame = insertionPoint;
 
+  if (parentFrame->GetType() == nsLayoutAtoms::frameSetFrame) {
+    // Just reframe the parent, since framesets are weird like that.
+    return RecreateFramesForContent(parentFrame->GetContent());
+  }
+  
   if (parentFrame->IsLeaf()) {
     // Nothing to do here; we shouldn't be constructing kids of leaves
     return NS_OK;
@@ -9040,6 +9045,11 @@ nsCSSFrameConstructor::ContentInserted(nsIContent*            aContainer,
                                            aContainer, aIndexInContainer);
   }
 
+  if (parentFrame->GetType() == nsLayoutAtoms::frameSetFrame) {
+    // Just reframe the parent, since framesets are weird like that.
+    return RecreateFramesForContent(parentFrame->GetContent());
+  }
+  
   // Don't construct kids of leaves
   if (parentFrame->IsLeaf()) {
     return NS_OK;
@@ -9602,6 +9612,11 @@ nsCSSFrameConstructor::ContentRemoved(nsIContent*     aContainer,
 
     parentFrame = insertionPoint;
 
+    if (parentFrame->GetType() == nsLayoutAtoms::frameSetFrame) {
+      // Just reframe the parent, since framesets are weird like that.
+      return RecreateFramesForContent(parentFrame->GetContent());
+    }
+
     // Examine the containing-block for the removed content and see if
     // :first-letter style applies.
     nsIFrame* containingBlock = GetFloatContainingBlock(parentFrame);
diff --git a/mozilla/layout/base/nsLayoutAtomList.h b/mozilla/layout/base/nsLayoutAtomList.h
index a145f1df73c..d2e0a7691d9 100644
--- a/mozilla/layout/base/nsLayoutAtomList.h
+++ b/mozilla/layout/base/nsLayoutAtomList.h
@@ -99,6 +99,7 @@ LAYOUT_ATOM(brFrame, "BRFrame")
 LAYOUT_ATOM(bulletFrame, "BulletFrame")
 LAYOUT_ATOM(columnSetFrame, "ColumnSetFrame")
 LAYOUT_ATOM(fieldSetFrame, "FieldSetFrame")
+LAYOUT_ATOM(frameSetFrame, "FrameSetFrame")
 LAYOUT_ATOM(gfxButtonControlFrame, "gfxButtonControlFrame")
 LAYOUT_ATOM(HTMLCanvasFrame, "HTMLCanvasFrame")
 LAYOUT_ATOM(subDocumentFrame, "subDocumentFrame")
diff --git a/mozilla/layout/generic/nsFrameSetFrame.cpp b/mozilla/layout/generic/nsFrameSetFrame.cpp
index 4609cfee3ad..6da6233f5a2 100644
--- a/mozilla/layout/generic/nsFrameSetFrame.cpp
+++ b/mozilla/layout/generic/nsFrameSetFrame.cpp
@@ -70,6 +70,7 @@
 #include "nsCSSAnonBoxes.h"
 #include "nsAutoPtr.h"
 #include "nsStyleSet.h"
+#include "nsLayoutAtoms.h"
 
 // masks for mEdgeVisibility
 #define LEFT_VIS   0x0001
@@ -1263,6 +1264,12 @@ nsHTMLFramesetFrame::Reflow(nsPresContext*          aPresContext,
   return NS_OK;
 }
 
+nsIAtom*
+nsHTMLFramesetFrame::GetType() const
+{
+  return nsLayoutAtoms::frameSetFrame;
+}
+
 PRBool
 nsHTMLFramesetFrame::IsLeaf() const
 {
diff --git a/mozilla/layout/generic/nsFrameSetFrame.h b/mozilla/layout/generic/nsFrameSetFrame.h
index 2ce5942ac36..3ac44cf5e35 100644
--- a/mozilla/layout/generic/nsFrameSetFrame.h
+++ b/mozilla/layout/generic/nsFrameSetFrame.h
@@ -152,6 +152,8 @@ public:
                     const nsHTMLReflowState& aReflowState,
                     nsReflowStatus&          aStatus);
 
+  virtual nsIAtom* GetType() const;
+
   virtual PRBool IsLeaf() const;
   
   NS_IMETHOD  VerifyTree() const;