diff -r 000000000000 -r 6474c204b198 content/base/src/nsDOMSettableTokenList.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/base/src/nsDOMSettableTokenList.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+/* 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/. */
+
+/*
+ * Implementation of DOMSettableTokenList specified by HTML5.
+ */
+
+#include "nsDOMSettableTokenList.h"
+#include "mozilla/dom/DOMSettableTokenListBinding.h"
+#include "mozilla/dom/Element.h"
+
+void
+nsDOMSettableTokenList::SetValue(const nsAString& aValue, mozilla::ErrorResult& rv)
+{
+  if (!mElement) {
+    return;
+  }
+
+  rv = mElement->SetAttr(kNameSpaceID_None, mAttrAtom, aValue, true);
+}
+
+JSObject*
+nsDOMSettableTokenList::WrapObject(JSContext *cx)
+{
+  return mozilla::dom::DOMSettableTokenListBinding::Wrap(cx, this);
+}