Give the undici shim's Dispatcher an explicit constructor

The implicit constructor forwarded its arguments to EventEmitter's options-taking constructor, which compiles to a deferred runtime fence. Dispatcher takes no options, so it calls super() directly.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/compiler/shims/undici/core/dispatcher.ts

@@ -38,6 +38,12 @@ export interface ResponseData {
 const defaultProfile: Profile = { major: 7 };
 
 export class Dispatcher extends EventEmitter {
+  // An explicit constructor: the implicit one forwards its arguments to
+  // EventEmitter's options-taking constructor, which stays a runtime fence.
+  constructor() {
+    super();
+  }
+
   dispatch(_options: DispatchOptions, _handler: DispatchHandlers): boolean {
     throw new Error("not implemented");
   }