JS: Add ClosureNamespaceAccess

javascript/ql/src/semmle/javascript/Closure.qll

@@ -15,6 +15,11 @@ module Closure {
     abstract string getClosureNamespace();
   }
 
+  /**
+   * A dataflow node that returns the value of a closure namespace.
+   */
+  abstract class ClosureNamespaceAccess extends ClosureNamespaceRef, DataFlow::SourceNode { }
+
   /**
    * A call to a method on the `goog.` namespace, as a closure reference.
    */
@@ -44,7 +49,7 @@ module Closure {
   /**
    * A call to `goog.require`.
    */
-  class ClosureRequireCall extends DefaultNamespaceRef {
+  class ClosureRequireCall extends DefaultNamespaceRef, ClosureNamespaceAccess {
     ClosureRequireCall() { getMethodName() = "require" }
   }
 
@@ -172,7 +177,7 @@ module Closure {
       result = getWrittenLibraryAccessPath(write)
     )
     or
-    result = node.(ClosureRequireCall).getClosureNamespace()
+    result = node.(ClosureNamespaceAccess).getClosureNamespace()
   }
 
   /**