JS: Add test

javascript/ql/test/library-tests/TaintTracking/factory-function.js

@@ -0,0 +1,27 @@
+import * as dummy from 'dummy';
+
+var objectA = function(){
+    return {};
+}
+objectA.set = function (obj){
+    sink(obj);
+};
+
+function factory() {
+    var objectB = function(){
+        return {};
+    }
+
+    objectB.set = function (obj){
+        sink(obj); // NOT OK
+    };
+    return objectB;
+}
+
+objectA.set(source());
+objectA.set(source());
+
+factory();
+b = factory();
+b.set(source())
+b.set(source())