JS: Move VarAccessBarrier outside the deprecated Configuration.qll file

Author: asgerf

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

@@ -2001,21 +2001,6 @@ deprecated private class CallAgainstEqualityCheck extends DerivedBarrierGuardNod
   override predicate appliesTo(Configuration cfg) { isBarrierGuardInternal(cfg, prev) }
 }
 
-/**
- * A guard node for a variable in a negative condition, such as `x` in `if(!x)`.
- * Can be added to a `isBarrier` in a data-flow configuration to block flow through such checks.
- */
-class VarAccessBarrier extends DataFlow::Node {
-  VarAccessBarrier() {
-    exists(ConditionGuardNode guard, SsaRefinementNode refinement |
-      this = DataFlow::ssaDefinitionNode(refinement) and
-      refinement.getGuard() = guard and
-      guard.getTest() instanceof VarAccess and
-      guard.getOutcome() = false
-    )
-  }
-}
-
 /**
  *  Holds if there is a path without unmatched return steps from `source` to `sink`.
  */

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

@@ -1708,3 +1708,18 @@ class RegExpCreationNode extends DataFlow::SourceNode {
     result = this.getAReference(DataFlow::TypeTracker::end())
   }
 }
+
+/**
+ * A guard node for a variable in a negative condition, such as `x` in `if(!x)`.
+ * Can be added to a `isBarrier` in a data-flow configuration to block flow through such checks.
+ */
+class VarAccessBarrier extends DataFlow::Node {
+  VarAccessBarrier() {
+    exists(ConditionGuardNode guard, SsaRefinementNode refinement |
+      this = DataFlow::ssaDefinitionNode(refinement) and
+      refinement.getGuard() = guard and
+      guard.getTest() instanceof VarAccess and
+      guard.getOutcome() = false
+    )
+  }
+}