diff --git a/content/media/webaudio/OscillatorNode.h b/content/media/webaudio/OscillatorNode.h
index a58e81de367..73a22abdba8 100644
--- a/content/media/webaudio/OscillatorNode.h
+++ b/content/media/webaudio/OscillatorNode.h
@@ -48,34 +48,6 @@ public:
   }
   void SetType(OscillatorType aType, ErrorResult& aRv)
   {
-    if (!Preferences::GetBool("media.webaudio.legacy.OscillatorNode")) {
-      // Do not accept the alternate enum values unless the legacy pref
-      // has been turned on.
-      switch (aType) {
-      case OscillatorType::_0:
-      case OscillatorType::_1:
-      case OscillatorType::_2:
-      case OscillatorType::_3:
-      case OscillatorType::_4:
-        // Do nothing in order to emulate setting an invalid enum value.
-        return;
-      default:
-        // Shut up the compiler warning
-        break;
-      }
-    }
-
-    // Handle the alternate enum values
-    switch (aType) {
-    case OscillatorType::_0: aType = OscillatorType::Sine; break;
-    case OscillatorType::_1: aType = OscillatorType::Square; break;
-    case OscillatorType::_2: aType = OscillatorType::Sawtooth; break;
-    case OscillatorType::_3: aType = OscillatorType::Triangle; break;
-    case OscillatorType::_4: aType = OscillatorType::Custom; break;
-    default:
-      // Shut up the compiler warning
-      break;
-    }
     if (aType == OscillatorType::Custom) {
       // ::Custom can only be set by setPeriodicWave().
       // https://github.com/WebAudio/web-audio-api/issues/105 for exception.
@@ -96,15 +68,7 @@ public:
   }
 
   void Start(double aWhen, ErrorResult& aRv);
-  void NoteOn(double aWhen, ErrorResult& aRv)
-  {
-    Start(aWhen, aRv);
-  }
   void Stop(double aWhen, ErrorResult& aRv);
-  void NoteOff(double aWhen, ErrorResult& aRv)
-  {
-    Stop(aWhen, aRv);
-  }
   void SetPeriodicWave(PeriodicWave& aPeriodicWave)
   {
     mPeriodicWave = &aPeriodicWave;
diff --git a/content/media/webaudio/test/test_oscillatorNode.html b/content/media/webaudio/test/test_oscillatorNode.html
index 3d4b36aa2a2..5eb48857433 100644
--- a/content/media/webaudio/test/test_oscillatorNode.html
+++ b/content/media/webaudio/test/test_oscillatorNode.html
@@ -23,9 +23,6 @@ addLoadEvent(function() {
   expectException(function() {
     osc.type = "custom";
   }, DOMException.INVALID_STATE_ERR);
-  expectException(function() {
-    osc.type = osc.CUSTOM;
-  }, DOMException.INVALID_STATE_ERR);
   is(osc.type, "sine", "Cannot set the type to custom");
   is(osc.frequency.value, 440, "Correct default frequency value");
   is(osc.detune.value, 0, "Correct default detine value");
@@ -38,8 +35,6 @@ addLoadEvent(function() {
     "triangle",
   ];
   for (var i = 0; i < types.length; ++i) {
-    osc.type = osc[types[i].toUpperCase()];
-    is(osc.type, types[i], "Correct alternname type enum value");
     osc.type = types[i];
   }
 
diff --git a/dom/webidl/OscillatorNode.webidl b/dom/webidl/OscillatorNode.webidl
index dd412406e1e..096732ff95a 100644
--- a/dom/webidl/OscillatorNode.webidl
+++ b/dom/webidl/OscillatorNode.webidl
@@ -11,9 +11,6 @@
  */
 
 enum OscillatorType {
-  // Hack: Use numbers to support alternate enum values
-  "0", "1", "2", "3", "4",
-
   "sine",
   "square",
   "sawtooth",
@@ -39,28 +36,3 @@ interface OscillatorNode : AudioNode {
 
 };
 
-/*
- * The origin of this IDL file is
- * https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#AlternateNames
- */
-partial interface OscillatorNode {
-    // Same as start()
-    [Throws,Pref="media.webaudio.legacy.OscillatorNode"]
-    void noteOn(double when);
-
-    // Same as stop()
-    [Throws,Pref="media.webaudio.legacy.OscillatorNode"]
-    void noteOff(double when);
-
-    [Pref="media.webaudio.legacy.OscillatorNode"]
-    const unsigned short SINE = 0;
-    [Pref="media.webaudio.legacy.OscillatorNode"]
-    const unsigned short SQUARE = 1;
-    [Pref="media.webaudio.legacy.OscillatorNode"]
-    const unsigned short SAWTOOTH = 2;
-    [Pref="media.webaudio.legacy.OscillatorNode"]
-    const unsigned short TRIANGLE = 3;
-    [Pref="media.webaudio.legacy.OscillatorNode"]
-    const unsigned short CUSTOM = 4;
-};
-
diff --git a/testing/profiles/prefs_general.js b/testing/profiles/prefs_general.js
index 9bfed49d4c2..126a2052095 100644
--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -146,7 +146,6 @@ user_pref("dom.gamepad.non_standard_events.enabled", true);
 
 // Enable Web Audio legacy APIs
 user_pref("media.webaudio.legacy.PannerNode", true);
-user_pref("media.webaudio.legacy.OscillatorNode", true);
 
 // Always use network provider for geolocation tests
 // so we bypass the OSX dialog raised by the corelocation provider