Made AudioNode an EventTarget

LayoutTests/webaudio/audionode.html

Index: LayoutTests/webaudio/audionode.html
diff --git a/LayoutTests/webaudio/audionode.html b/LayoutTests/webaudio/audionode.html
index dd0dc32958a5ed2f8d7baf4c4d64de134ad7f524..5fdcfd0707648a042835b6405ac8faa28b38f0a5 100644
--- a/LayoutTests/webaudio/audionode.html
+++ b/LayoutTests/webaudio/audionode.html
@@ -101,6 +101,18 @@ function runTest() {
         testPassed("exception thrown when creating audio context with not enough arguments.");
     }
 
+    // Ensure it is an EventTarget
+    try {
+        window.audioNodeIsEventTarget = false;
+        audioNode.addEventListener('testEvent', function(){
+            audioNodeIsEventTarget = true;
+        });
+        audioNode.dispatchEvent(new Event('testEvent'));
+        shouldBeTrue('audioNodeIsEventTarget');

[haraken, 2013/04/15 00:01:25]

Nit: You can write testPassed() line inside the event listener. Then
audioNodeIsEventTarget won't be needed.

+    } catch(e) {
+        testFailed("exception shouldn't be thrown when testing whether audio node is an event target");
+    }
+
     finishJSTest();
 }