Added constructor for AudioContext for dartc and frog

client/dom/src/_FactoryProviders.dart

Index: client/dom/src/_FactoryProviders.dart
diff --git a/client/dom/src/_FactoryProviders.dart b/client/dom/src/_FactoryProviders.dart
index 8589e09c77742b3ce9d507ed858899c760da5cf3..ccf83401be0019abc7797af0ef48e1692e103c42 100644
--- a/client/dom/src/_FactoryProviders.dart
+++ b/client/dom/src/_FactoryProviders.dart
@@ -6,6 +6,13 @@
 // These factory methods could all live in one factory provider class but dartc
 // has a bug (5399939) preventing that.
 
+class _AudioContextFactoryProvider {
+
+  factory AudioContext() { return create(); }
+
+  static AudioContext create() native;
+}
+
 class _FileReaderFactoryProvider {
 
   factory FileReader() { return create(); }