Bug 725770. r=bz

docshell/base/Makefile.in

@@ -94,4 +94,7 @@ LOCAL_INCLUDES += \
   -I$(topsrcdir)/dom/base \
   -I$(topsrcdir)/layout/base \
   -I$(topsrcdir)/xpcom/ds \
+  -I$(topsrcdir)/layout/generic \
+  -I$(topsrcdir)/layout/xul/base/src \
+  -I$(topsrcdir)/content/base/src \
   $(NULL)

docshell/base/nsDocShell.cpp

@@ -170,6 +170,7 @@
 #include "nsEventStateManager.h"
 
 #include "nsIFrame.h"
+#include "nsSubDocumentFrame.h"
 
 // for embedding
 #include "nsIWebBrowserChromeFocus.h"
@@ -7162,7 +7163,7 @@ nsDocShell::RestoreFromHistory()
     // Make sure to blow away our mLoadingURI just in case.  No loads
     // from inside this pagehide.
     mLoadingURI = nullptr;
-    
+
     // Notify the old content viewer that it's being hidden.
     FirePageHideNotification(!mSavingOldViewer);
 
@@ -7243,6 +7244,17 @@ nsDocShell::RestoreFromHistory()
         }
     }
 
+    nsCOMPtr<nsIContent> container;
+    nsCOMPtr<nsIDocument> sibling;
+    if (rootViewParent && rootViewParent->GetParent()) {
+        nsIFrame* frame = rootViewParent->GetParent()->GetFrame();
+        container = frame ? frame->GetContent() : nullptr;
+    }
+    if (rootViewSibling) {
+        nsIFrame *frame = rootViewSibling->GetFrame();
+        sibling = frame ? frame->PresContext()->PresShell()->GetDocument() : nullptr;
+    }
+
     // Transfer ownership to mContentViewer.  By ensuring that either the
     // docshell or the session history, but not both, have references to the
     // content viewer, we prevent the viewer from being torn down after
@@ -7331,7 +7343,7 @@ nsDocShell::RestoreFromHistory()
 
     // mLSHE is now our currently-loaded document.
     SetHistoryEntry(&mOSHE, mLSHE);
-    
+
     // XXX special wyciwyg handling in Embed()?
 
     // We aren't going to restore any items from the LayoutHistoryState,
@@ -7445,10 +7457,20 @@ nsDocShell::RestoreFromHistory()
     nsIView *newRootView = newVM ? newVM->GetRootView() : nullptr;
 
     // Insert the new root view at the correct location in the view tree.
-    if (rootViewParent) {
+    if (container) {
+        nsSubDocumentFrame* subDocFrame = do_QueryFrame(container->GetPrimaryFrame());
+        rootViewParent = subDocFrame ? subDocFrame->EnsureInnerView() : nullptr;
+    }
+    if (sibling &&
+        sibling->GetShell() &&
+        sibling->GetShell()->GetViewManager()) {
+        rootViewSibling = sibling->GetShell()->GetViewManager()->GetRootView();
+    } else {
+        rootViewSibling = nullptr;
+    }
+    if (rootViewParent && newRootView && newRootView->GetParent() != rootViewParent) {
         nsIViewManager *parentVM = rootViewParent->GetViewManager();
-
-        if (parentVM && newRootView) {
+        if (parentVM) {
             // InsertChild(parent, child, sib, true) inserts the child after
             // sib in content order, which is before sib in view order. BUT
             // when sib is null it inserts at the end of the the document