Add webkitAudioPannerNode as an optional name

tests/html/audiocontext_test.dart

 library AudioContextTest;
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_individual_config.dart';
 import 'dart:html';
 import 'dart:typed_data';
 import 'dart:web_audio';
 import 'dart:async';
 
 main() {
 
   useHtmlIndividualConfiguration();
 
   var isAudioContext =
       predicate((x) => x is AudioContext, 'is an AudioContext');
 
   group('supported', () {
     test('supported', () {
       expect(AudioContext.supported, true);
     });
   });
 
   group('functional', () {
+    var context;

[terry, 2015/01/23 19:58:09]

This doesn't need to be broken out?  Assumed this was done for debugging?

[Alan Knight, 2015/01/23 20:15:01]

When I made too many different tests you started getting errors about audio
resources being unavailable, so I think there are limits and it's better to just
allocate one.

+    if (AudioContext.supported) {
+      context = new AudioContext();
+    }
+    
     test('constructorTest', () {
       if(AudioContext.supported) {
-        var ctx = new AudioContext();
-        expect(ctx, isNotNull);
-        expect(ctx, isAudioContext);
+        expect(context, isNotNull);
+        expect(context, isAudioContext);
       }
     });
 
     test('audioRenames', () {
       if(AudioContext.supported) {
-        AudioContext context = new AudioContext();
         GainNode gainNode = context.createGain();
         gainNode.connectNode(context.destination);
         expect(gainNode is GainNode, isTrue);
 
         expect(context.createAnalyser() is AnalyserNode, isTrue);
         expect(context.createChannelMerger() is AudioNode, isTrue);
         expect(context.createChannelSplitter() is AudioNode, isTrue);
         expect(context.createOscillator() is OscillatorNode, isTrue);
         expect(context.createPanner() is PannerNode, isTrue);
         expect(context.createScriptProcessor(4096) is ScriptProcessorNode,
@@ skipping 16 matching lines @@
           }
           alreadyCalled = true;
         });
         return completer.future;
       }
     });
     */
 
     test('oscillatorTypes', () {
       if(AudioContext.supported) {
-        AudioContext context = new AudioContext();
         OscillatorNode oscillator = context.createOscillator();
         oscillator.connectNode(context.destination);
 
         oscillator.type = 'sawtooth';
         expect(oscillator.type, equals('sawtooth'));
 
         oscillator.type = 'sine';
         expect(oscillator.type, equals('sine'));
 
         oscillator.type = 'square';
         expect(oscillator.type, equals('square'));
 
         oscillator.type = 'triangle';
         expect(oscillator.type, equals('triangle'));
 
         //expect(() => oscillator.type = 7, throws); Firefox does not throw, it
         //simply ignores this value.
         expect(oscillator.type, equals('triangle'));
 
         // Firefox does not throw when it receives invalid values; it simply
         // ignores them.
         //expect(() => oscillator.type = ['heap object not a string'], throws);
         expect(oscillator.type, equals('triangle'));
       }
     });
   });
 }