test: force context allocation in test module

V8's behavior changed in c3bd741efd. Top-level variables
in a module are no longer context-allocated by default.

PR-URL: #18312
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/fixtures/es-modules/loop.mjs

@@ -7,4 +7,7 @@ while (t > 0) {
     console.log(`Outputed message #${k++}`);
   }
 }
-process.exit(55);
+process.exit(55);
+
+// test/parallel/test-inspector-esm.js expects t and k to be context-allocated.
+(function force_context_allocation() { return t + k; })