JS: Hide captured nodes in path explanations

Author: asgerf

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

@@ -1462,6 +1462,9 @@ class MidPathNode extends PathNode, MkMidNode {
     or
     // Skip the synthetic 'this' node, as a ThisExpr will be the next node anyway
     nd = DataFlow::thisNode(_)
+    or
+    // Skip captured variable nodes as the successor will be a use of that variable anyway.
+    nd = DataFlow::capturedVariableNode(_)
   }
 }
 

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

@@ -1245,6 +1245,15 @@ module DataFlow {
     }
   }
 
+  /**
+   * INTERNAL. DO NOT USE.
+   *
+   * Gets a data flow node representing the given captured variable.
+   */
+  Node capturedVariableNode(LocalVariable variable) {
+    result = TCapturedVariableNode(variable)
+  }
+
   /**
    * Gets the data flow node corresponding to `nd`.
    *