use the number guard in existing queries that contained typeof checks

javascript/ql/lib/semmle/javascript/security/dataflow/UnsafeJQueryPluginCustomizations.qll

@@ -153,6 +153,16 @@ module UnsafeJQueryPlugin {
     }
   }
 
+  /** A guard that checks whether `x` is a number. */
+  class NumberGuard extends TaintTracking::SanitizerGuardNode instanceof DataFlow::CallNode {
+    Expr x;
+    boolean polarity;
+
+    NumberGuard() { TaintTracking::isNumberGuard(this, x, polarity) }
+
+    override predicate sanitizes(boolean outcome, Expr e) { e = x and outcome = polarity }
+  }
+
   /**
    * The client-provided options object for a jQuery plugin, considered as a source for unsafe jQuery plugins.
    */