--- a/xpcom/ds/nsAtom.h
+++ b/xpcom/ds/nsAtom.h
@@ -111,16 +111,20 @@ protected:
 class nsStaticAtom : public nsAtom
 {
 public:
   // These are deleted so it's impossible to RefPtr<nsStaticAtom>. Raw
   // nsStaticAtom atoms should be used instead.
   MozExternalRefCountType AddRef() = delete;
   MozExternalRefCountType Release() = delete;
 
+  already_AddRefed<nsAtom> ToAddRefed() {
+    return already_AddRefed<nsAtom>(static_cast<nsAtom*>(this));
+  }
+
 private:
   friend class nsAtomFriend;
 
   // Construction is done entirely by |friend|s.
   nsStaticAtom(const char16_t* aString, uint32_t aLength, uint32_t aHash)
     : nsAtom(aString, aLength, aHash)
   {}
 };