--- a/content/html/content/public/HTMLAudioElement.h
+++ b/content/html/content/public/HTMLAudioElement.h
@@ -42,19 +42,17 @@ public:
   virtual nsresult Clone(nsINodeInfo *aNodeInfo, nsINode **aResult) const;
   virtual nsresult SetAcceptHeader(nsIHttpChannel* aChannel);
 
   virtual nsIDOMNode* AsDOMNode() { return this; }
 
   // WebIDL
 
   static already_AddRefed<HTMLAudioElement> Audio(const GlobalObject& global,
-                                                  ErrorResult& aRv);
-  static already_AddRefed<HTMLAudioElement> Audio(const GlobalObject& global,
-                                                  const nsAString& src,
+                                                  const Optional<nsAString>& src,
                                                   ErrorResult& aRv);
 
   void MozSetup(uint32_t aChannels, uint32_t aRate, ErrorResult& aRv);
 
   uint32_t MozWriteAudio(const Float32Array& aData, ErrorResult& aRv)
   {
     return MozWriteAudio(aData.Data(), aData.Length(), aRv);
   }

--- a/content/html/content/src/HTMLAudioElement.cpp
+++ b/content/html/content/src/HTMLAudioElement.cpp
@@ -51,17 +51,19 @@ HTMLAudioElement::HTMLAudioElement(alrea
 }
 
 HTMLAudioElement::~HTMLAudioElement()
 {
 }
 
 
 already_AddRefed<HTMLAudioElement>
-HTMLAudioElement::Audio(const GlobalObject& aGlobal, ErrorResult& aRv)
+HTMLAudioElement::Audio(const GlobalObject& aGlobal,
+                        const Optional<nsAString>& aSrc,
+                        ErrorResult& aRv)
 {
   nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(aGlobal.Get());
   nsIDocument* doc;
   if (!win || !(doc = win->GetExtantDoc())) {
     aRv.Throw(NS_ERROR_FAILURE);
     return nullptr;
   }
 
@@ -71,25 +73,18 @@ HTMLAudioElement::Audio(const GlobalObje
                                         nsIDOMNode::ELEMENT_NODE);
 
   nsRefPtr<HTMLAudioElement> audio = new HTMLAudioElement(nodeInfo.forget());
   audio->SetHTMLAttr(nsGkAtoms::preload, NS_LITERAL_STRING("auto"), aRv);
   if (aRv.Failed()) {
     return nullptr;
   }
 
-  return audio.forget();
-}
-
-already_AddRefed<HTMLAudioElement>
-HTMLAudioElement::Audio(const GlobalObject& aGlobal, const nsAString& aSrc, ErrorResult& aRv)
-{
-  nsRefPtr<HTMLAudioElement> audio = Audio(aGlobal, aRv);
-  if (audio) {
-    aRv = audio->SetSrc(aSrc);
+  if (aSrc.WasPassed()) {
+    aRv = audio->SetSrc(aSrc.Value());
   }
 
   return audio.forget();
 }
 
 void
 HTMLAudioElement::MozSetup(uint32_t aChannels, uint32_t aRate, ErrorResult& aRv)
 {

--- a/dom/webidl/HTMLAudioElement.webidl
+++ b/dom/webidl/HTMLAudioElement.webidl
@@ -6,18 +6,17 @@
  * The origin of this IDL file is
  * http://www.whatwg.org/specs/web-apps/current-work/#the-audio-element
  *
  * © Copyright 2004-2011 Apple Computer, Inc., Mozilla Foundation, and
  * Opera Software ASA. You are granted a license to use, reproduce
  * and create derivative works of this document.
  */
 
-[NamedConstructor=Audio(),
- NamedConstructor=Audio(DOMString src)]
+[NamedConstructor=Audio(optional DOMString src)]
 interface HTMLAudioElement : HTMLMediaElement {};
 
 partial interface HTMLAudioElement
 {
   // Setup the audio stream for writing
   [Pref="media.audio_data.enabled", Throws]
   void mozSetup(unsigned long channels, unsigned long rate);