--- a/dom/base/nsIContent.h
+++ b/dom/base/nsIContent.h
@@ -322,16 +322,28 @@ public:
     return IsMathMLElement() && IsNodeInternal(aFirst, aArgs...);
   }
   inline bool IsActiveChildrenElement() const
   {
     return mNodeInfo->Equals(nsGkAtoms::children, kNameSpaceID_XBL) &&
            GetBindingParent();
   }
 
+  bool IsGeneratedContentContainerForBefore() const
+  {
+    return IsRootOfNativeAnonymousSubtree() &&
+           mNodeInfo->NameAtom() == nsGkAtoms::mozgeneratedcontentbefore;
+  }
+
+  bool IsGeneratedContentContainerForAfter() const
+  {
+    return IsRootOfNativeAnonymousSubtree() &&
+           mNodeInfo->NameAtom() == nsGkAtoms::mozgeneratedcontentafter;
+  }
+
   /**
    * Set attribute values. All attribute values are assumed to have a
    * canonical string representation that can be used for these
    * methods. The SetAttr method is assumed to perform a translation
    * of the canonical form into the underlying content specific
    * form.
    *
    * @param aNameSpaceID the namespace of the attribute