diff -r 000000000000 -r 6474c204b198 content/base/src/nsMappedAttributeElement.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/base/src/nsMappedAttributeElement.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set tw=80 expandtab softtabstop=2 ts=2 sw=2: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMappedAttributeElement.h"
+#include "nsIDocument.h"
+
+nsresult
+nsMappedAttributeElement::WalkContentStyleRules(nsRuleWalker* aRuleWalker)
+{
+  mAttrsAndChildren.WalkMappedAttributeStyleRules(aRuleWalker);
+  return NS_OK;
+}
+
+bool
+nsMappedAttributeElement::SetMappedAttribute(nsIDocument* aDocument,
+                                             nsIAtom* aName,
+                                             nsAttrValue& aValue,
+                                             nsresult* aRetval)
+{
+  NS_PRECONDITION(aDocument == GetCurrentDoc(), "Unexpected document");
+  nsHTMLStyleSheet* sheet = aDocument ?
+    aDocument->GetAttributeStyleSheet() : nullptr;
+
+  *aRetval = mAttrsAndChildren.SetAndTakeMappedAttr(aName, aValue,
+                                                    this, sheet);
+  return true;
+}
+
+nsMapRuleToAttributesFunc
+nsMappedAttributeElement::GetAttributeMappingFunction() const
+{
+  return &MapNoAttributesInto;
+}
+
+void
+nsMappedAttributeElement::MapNoAttributesInto(const nsMappedAttributes* aAttributes,
+                                              nsRuleData* aData)
+{
+}