JS: cache things

javascript/ql/src/semmle/javascript/GlobalAccessPaths.qll

@@ -41,6 +41,7 @@ module GlobalAccessPath {
    * })(NS = NS || {});
    * ``` 
    */
+  cached
   string fromReference(DataFlow::Node node) {
     result = fromReference(node.getImmediatePredecessor())
     or
@@ -142,6 +143,7 @@ module GlobalAccessPath {
    *  })(foo = foo || {});
    * ```
    */
+  cached
   string fromRhs(DataFlow::Node node) {
     exists(DataFlow::SourceNode base, string baseName, string name |
       node = base.getAPropertyWrite(name).getRhs() and

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

@@ -693,6 +693,7 @@ class ClassNode extends DataFlow::SourceNode {
   /**
    * Gets a dataflow node that refers to this class object.
    */
+  cached
   DataFlow::SourceNode getAClassReference() {
     result = getAClassReference(DataFlow::TypeTracker::end())
   }
@@ -730,6 +731,7 @@ class ClassNode extends DataFlow::SourceNode {
   /**
    * Gets a dataflow node that refers to an instance of this class.
    */
+  cached
   DataFlow::SourceNode getAnInstanceReference() {
     result = getAnInstanceReference(DataFlow::TypeTracker::end())
   }