Merge pull request #2102 from erik-krogh/deferredModel

JS: add Deferred model in js/use-of-returnless-function

javascript/ql/test/library-tests/TaintTracking/promise.js

@@ -11,4 +11,4 @@ function closure() {
   let resolver = Promise.withResolver();
   resolver.resolve(source());
   sink(resolver.promise); // NOT OK
-}
+}

javascript/ql/test/query-tests/Statements/UseOfReturnlessFunction/tst.js

@@ -82,4 +82,10 @@
 	
 	var baz = [1,2,3].filter(n => {n === 3}) // OK
 	console.log(baz);
+	
+	class Deferred {
+	
+	}
+	
+	new Deferred().resolve(onlySideEffects()); // OK
 })();