JS: Add test with type casts

Author: asgerf

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

@@ -48,4 +48,6 @@
 | subtype.ts:7:13:7:15 | req | 'express'.Request |
 | subtype.ts:13:13:13:15 | req | 'express'.Request |
 | subtype.ts:19:13:19:15 | req | 'express'.Request |
+| typeCast.ts:4:16:4:35 | e as express.Request | 'express'.Request |
+| typeCast.ts:5:16:5:33 | <express.Request>e | 'express'.Request |
 | varAssignment.ts:4:9:4:11 | req | 'express'.Request |

javascript/ql/test/library-tests/UnderlyingTypes/typeCast.ts

@@ -0,0 +1,7 @@
+import * as express from 'express';
+
+function t1(e) {
+    var req1 = e as express.Request; // $ hasUnderlyingType='express'.Request
+    var req2 = <express.Request>e; // $ hasUnderlyingType='express'.Request
+    var req3 = e satisfies express.Request;
+}