Add constructors for WebAudio nodes

third_party/WebKit/Source/modules/webaudio/PannerOptions.idl

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// See https://webaudio.github.io/web-audio-api/#panneroptions
+dictionary PannerOptions : AudioNodeOptions {
+    PanningModelType panningModel;
+    DistanceModelType distanceModel;
+
+    float positionX;
+    float positionY;
+    float positionZ;
+    float orientationX;
+    float orientationY;
+    float orientationZ;
+
+    float refDistance;
+    float maxDistance;
+    float rolloffFactor;
+    float coneInnerAngle;
+    float coneOuterAngle;
+    float coneOuterGain;
+};