Support for callbacks on ScriptProcessNode.

tools/dom/templates/html/impl/impl_ScriptProcessorNode.darttemplate

Index: tools/dom/templates/html/impl/impl_ScriptProcessorNode.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_ScriptProcessorNode.darttemplate b/tools/dom/templates/html/impl/impl_ScriptProcessorNode.darttemplate
index 52ba80f348c4b834bd161c3cfda345898bdbb1c3..15bf88ed9370beb4169c7e3661ccc348bd83a128 100644
--- a/tools/dom/templates/html/impl/impl_ScriptProcessorNode.darttemplate
+++ b/tools/dom/templates/html/impl/impl_ScriptProcessorNode.darttemplate
@@ -26,16 +26,18 @@ $(ANNOTATIONS)class $CLASSNAME$EXTENDS$NATIVESPEC {
             controller.add(audioData);
           }
         };
+      _setEventListener(callback);
+      _eventStream = controller.stream;
+    }
+    return _eventStream;
+  }
+
 $if DART2JS
+    _setEventListener(callback) {
       JS('void', '#.onaudioprocess = #', this,
           convertDartClosureToJS(callback, 1));
-$else
-      // TODO(podivilov): Implement on Dartium.
+    }
 $endif
 
-      _eventStream = controller.stream;
-    }
-    return _eventStream;
-  }
 $!MEMBERS
 }