diff --git a/content/base/src/nsFrameLoader.cpp b/content/base/src/nsFrameLoader.cpp
index 8c3ddded2606..97adec4b5109 100644
--- a/content/base/src/nsFrameLoader.cpp
+++ b/content/base/src/nsFrameLoader.cpp
@@ -450,17 +450,8 @@ nsFrameLoader::EnsureDocShell()
       }
     }
 
-    if (isContent) {
-      // The web shell's type is content.
-
-      docShellAsItem->SetItemType(nsIDocShellTreeItem::typeContent);
-    } else {
-      // Inherit our type from our parent webshell.  If it is
-      // chrome, we'll be chrome.  If it is content, we'll be
-      // content.
-
-      docShellAsItem->SetItemType(parentType);
-    }
+    PRInt32 shellType = isContent ? nsIDocShellTreeItem::typeContent : parentType;
+    docShellAsItem->SetItemType(shellType);
 
     parentAsNode->AddChild(docShellAsItem);
 
@@ -469,7 +460,8 @@ nsFrameLoader::EnsureDocShell()
       parentAsItem->GetTreeOwner(getter_AddRefs(parentTreeOwner));
 
       if(parentTreeOwner) {
-        PRBool is_primary = value.Equals(NS_LITERAL_STRING("content-primary"));
+        PRBool is_primary = shellType == nsIDocShellTreeItem::typeChrome &&
+                            value.Equals(NS_LITERAL_STRING("content-primary"));
 
         parentTreeOwner->ContentShellAdded(docShellAsItem, is_primary,
                                            value.get());
diff --git a/layout/generic/nsFrameFrame.cpp b/layout/generic/nsFrameFrame.cpp
index 8bfcb5ee9b54..3a7f6ddcbd70 100644
--- a/layout/generic/nsFrameFrame.cpp
+++ b/layout/generic/nsFrameFrame.cpp
@@ -683,7 +683,10 @@ nsHTMLFrameOuterFrame::AttributeChanged(nsIPresContext* aPresContext,
       nsCOMPtr<nsIDocShellTreeOwner> parentTreeOwner;
       parentAsItem->GetTreeOwner(getter_AddRefs(parentTreeOwner));
       if (parentTreeOwner) {
+        PRInt32 shellType;
+        parentAsItem->GetItemType(&shellType);
         PRBool is_primary_content =
+          shellType == nsIDocShellTreeItem::typeChrome &&
           value.EqualsIgnoreCase("content-primary");
 
         parentTreeOwner->ContentShellAdded(docShellAsItem, is_primary_content,
diff --git a/layout/html/document/src/nsFrameFrame.cpp b/layout/html/document/src/nsFrameFrame.cpp
index 8bfcb5ee9b54..3a7f6ddcbd70 100644
--- a/layout/html/document/src/nsFrameFrame.cpp
+++ b/layout/html/document/src/nsFrameFrame.cpp
@@ -683,7 +683,10 @@ nsHTMLFrameOuterFrame::AttributeChanged(nsIPresContext* aPresContext,
       nsCOMPtr<nsIDocShellTreeOwner> parentTreeOwner;
       parentAsItem->GetTreeOwner(getter_AddRefs(parentTreeOwner));
       if (parentTreeOwner) {
+        PRInt32 shellType;
+        parentAsItem->GetItemType(&shellType);
         PRBool is_primary_content =
+          shellType == nsIDocShellTreeItem::typeChrome &&
           value.EqualsIgnoreCase("content-primary");
 
         parentTreeOwner->ContentShellAdded(docShellAsItem, is_primary_content,