Add webkitAudioPannerNode as an optional name

sdk/lib/web_audio/dart2js/web_audio_dart2js.dart

Index: sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
diff --git a/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart b/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
index 40c3706bfe904f5ac90f494049082b435a1b0ef6..9a47ceb682b69adfca513d1d9b57fce87780b3c2 100644
--- a/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
+++ b/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
@@ -885,7 +885,7 @@ class OscillatorNode extends AudioSourceNode {
 @DomName('PannerNode')
 // https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#PannerNode
 @Experimental()
-@Native("PannerNode,AudioPannerNode")
+@Native("PannerNode,AudioPannerNode,webkitAudioPannerNode")
 class PannerNode extends AudioNode {
   // To suppress missing implicit constructor warnings.
   factory PannerNode._() { throw new UnsupportedError("Not supported"); }