JS: Add a few more tests

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

@@ -1,9 +1,26 @@
+import 'dummy';
+
 function test() {
   let taint = source();
-  
+
   sink({ ...taint }); // NOT OK
   sink({ f: 'hello', ...taint, g: 'world' }); // NOT OK
 
   sink([ ...taint ]); // NOT OK
   sink([ 1, 2, ...taint, 3 ]); // NOT OK
+
+  fn1(...['x', taint, 'z']);
+  fn2.apply(undefined, ['x', taint, 'z']);
+}
+
+function fn1(x, y, z) {
+  sink(x);
+  sink(y); // NOT OK
+  sink(z);
+}
+
+function fn2(x, y, z) {
+  sink(x);
+  sink(y); // NOT OK
+  sink(z);
 }