JS: Add interface for isBarrier in/out

Author: asgerf

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

@@ -166,6 +166,26 @@ abstract class Configuration extends string {
     )
   }
 
+  /**
+   * Holds if flow into `node` is prohibited.
+   */
+  predicate isBarrierIn(DataFlow::Node node) { none() }
+
+  /**
+   * Holds if flow out `node` is prohibited.
+   */
+  predicate isBarrierOut(DataFlow::Node node) { none() }
+
+  /**
+   * Holds if flow into `node` is prohibited for the flow label `lbl`.
+   */
+  predicate isBarrierIn(DataFlow::Node node, FlowLabel lbl) { none() }
+
+  /**
+   * Holds if flow out `node` is prohibited for the flow label `lbl`.
+   */
+  predicate isBarrierOut(DataFlow::Node node, FlowLabel lbl) { none() }
+
   /**
    * Holds if flow from `pred` to `succ` is prohibited.
    */