fix(ext/node): stub ServerResponse#flushHeaders (#21526)

This commit adds a no-op flushHeaders method to the ServerResponse
object. It is a nop because the ServerResponse implementation is based
on top of the Deno server API instead of the Node `OutgoingMessage`
base.

Fixes #21509

1 files changed, 4 insertions, 0 deletions

diff --git a/ext/node/polyfills/http.ts b/ext/node/polyfills/http.ts
index a694c9e9b..27fc577c0 100644
--- a/ext/node/polyfills/http.ts
+++ b/ext/node/polyfills/http.ts
@@ -1459,6 +1459,10 @@ export class ServerResponse extends NodeWritable {
     return super.end(chunk, encoding, cb);
   }
 
+  flushHeaders() {
+    // no-op
+  }
+
   // Undocumented API used by `npm:compression`.
   _implicitHeader() {
     this.writeHead(this.statusCode);