update test to not use private class

Author: erik-krogh

javascript/ql/test/library-tests/frameworks/EventEmitter/test.ql

@@ -1,6 +1,8 @@
 import javascript
 
 query predicate taintSteps(DataFlow::Node pred, DataFlow::Node succ) {
-  any(EventEmitter::EventEmitterTaintStep step).step(pred, succ)
+  exists(DataFlow::AdditionalFlowStep step | 
+    step.step(pred, succ)
+  )
 }