JS: make higherOrderCall private

Author: asger-semmle

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

@@ -708,7 +708,7 @@ private predicate summarizedHigherOrderCall(
  * - The flow label mapping of the summary corresponds to the transformation from `arg` to the
  *   invocation of the callback.
  */
-predicate higherOrderCall(
+private predicate higherOrderCall(
   DataFlow::Node arg, DataFlow::SourceNode callback, int i, DataFlow::Configuration cfg,
   PathSummary summary
 ) {