JS: Use getABoundFunctionValue in PostMessageEventHandler

javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll

@@ -127,6 +127,8 @@ module DataFlow {
      * possibly derived from a partial function invocation.
      */
     final FunctionNode getABoundFunctionValue(int boundArgs) {
+      result = getAFunctionValue() and boundArgs = 0
+      or
       CallGraph::getABoundFunctionReference(result, boundArgs).flowsTo(this)
     }
 

javascript/ql/src/semmle/javascript/security/dataflow/DOM.qll

@@ -174,18 +174,20 @@ private module PersistentWebStorage {
  * An event handler that handles `postMessage` events.
  */
 class PostMessageEventHandler extends Function {
+  int paramIndex;
+
   PostMessageEventHandler() {
-    exists(CallExpr addEventListener |
-      addEventListener.getCallee().accessesGlobal("addEventListener") and
+    exists(DataFlow::CallNode addEventListener |
+      addEventListener = DataFlow::globalVarRef("addEventListener").getACall() and
       addEventListener.getArgument(0).mayHaveStringValue("message") and
-      addEventListener.getArgument(1).analyze().getAValue().(AbstractFunction).getFunction() = this
+      addEventListener.getArgument(1).getABoundFunctionValue(paramIndex).getFunction() = this
     )
   }
 
   /**
    * Gets the parameter that contains the event.
    */
-  SimpleParameter getEventParameter() { result = getParameter(0) }
+  Parameter getEventParameter() { result = getParameter(paramIndex) }
 }
 
 /**