Fix a bug in overload dispatch.

tests/html/audiocontext_test.dart

Index: tests/html/audiocontext_test.dart
diff --git a/tests/html/audiocontext_test.dart b/tests/html/audiocontext_test.dart
index 6e9e02cb14af64a883852389dec419521e4434c9..7305a0f3b4c0c4d81a87a0f5453e2341a5025f51 100644
--- a/tests/html/audiocontext_test.dart
+++ b/tests/html/audiocontext_test.dart
@@ -9,7 +9,18 @@ main() {
 
   test('constructorTest', () {
       var ctx = new AudioContext();
-      Expect.isTrue(ctx != null);
+      Expect.isNotNull(ctx);
       Expect.isTrue(ctx is AudioContext);
   });
+  test('createBuffer', () {
+      var ctx = new AudioContext();
+      ArrayBufferView arrayBufferView = new Float32Array.fromList([]);
+      try {
+        // Test that native overload is chosen correctly. Native implementation
+        // should throw 'SYNTAX_ERR' DOMException because the buffer is empty.
+        AudioBuffer buffer = ctx.createBuffer(arrayBufferView.buffer, false);
+      } catch(var e) {
+        Expect.equals(DOMException.SYNTAX_ERR, e.code);
+      }
+  });
 }