Change the default panning mode from HRTF to equal-power

Source/modules/webaudio/PannerNode.cpp

Index: Source/modules/webaudio/PannerNode.cpp
diff --git a/Source/modules/webaudio/PannerNode.cpp b/Source/modules/webaudio/PannerNode.cpp
index bb2f85bcade245d84a983228dafad6c6d4f9ef87..dce477e4bc33d17f9a668e1a87f603398986e091 100644
--- a/Source/modules/webaudio/PannerNode.cpp
+++ b/Source/modules/webaudio/PannerNode.cpp
@@ -48,7 +48,7 @@ static void fixNANs(double &x)
 
 PannerNode::PannerNode(AudioContext* context, float sampleRate)
     : AudioNode(context, sampleRate)
-    , m_panningModel(Panner::PanningModelHRTF)
+    , m_panningModel(Panner::PanningModelEqualPower)
     , m_distanceModel(DistanceEffect::ModelInverse)
     , m_position(0, 0, 0)
     , m_orientation(1, 0, 0)
@@ -198,7 +198,7 @@ String PannerNode::panningModel() const
         return "HRTF";
     default:
         ASSERT_NOT_REACHED();
-        return "HRTF";
+        return "equalpower";
     }
 }