JS: Add test for class instance escaping into dependency

Author: asgerf

javascript/ql/test/library-tests/EndpointNaming/EndpointNaming.expected

@@ -1,4 +1,5 @@
 testFailures
+| pack1/main.js:19:6:19:10 |  | Unexpected result: name=(pack1).InternalClass.prototype.m |
 ambiguousPreferredPredecessor
 | pack2/lib.js:1:1:3:1 | def moduleImport("pack2").getMember("exports").getMember("lib").getMember("LibClass").getInstance() |
 | pack2/lib.js:8:22:8:34 | def moduleImport("pack2").getMember("exports").getMember("lib").getMember("LibClass").getMember("foo") |

javascript/ql/test/library-tests/EndpointNaming/pack1/main.js

@@ -13,3 +13,9 @@ export function getEscapingInstance() {
 } // $ name=(pack1).getEscapingInstance
 
 export function publicFunction() {} // $ name=(pack1).publicFunction
+
+// Escapes into an upstream library, but is not exposed downstream
+class InternalClass {
+    m() {}
+}
+require('foo').bar(new InternalClass());