Fix how we enable fetch streams. (firebase#7569)

* Fix how we enable fetch streams.

* Create nervous-cups-relax.md

Author: wu-hui

.changeset/nervous-cups-relax.md

@@ -0,0 +1,6 @@
+---
+"@firebase/firestore": patch
+"@firebase/webchannel-wrapper": patch
+---
+
+Fix how we enable fetch streams.

packages/firestore/src/platform/browser/webchannel_connection.ts

@@ -22,7 +22,6 @@ import {
   WebChannel,
   WebChannelError,
   WebChannelOptions,
-  FetchXmlHttpFactory,
   XhrIo,
   getStatEventTarget,
   EventTarget,
@@ -209,7 +208,7 @@ export class WebChannelConnection extends RestConnection {
     }
 
     if (this.useFetchStreams) {
-      request.xmlHttpFactory = new FetchXmlHttpFactory({});
+      request.useFetchStreams = true;
     }
 
     this.modifyHeadersForRequest(

packages/webchannel-wrapper/src/index.d.ts

@@ -108,6 +108,7 @@ export interface WebChannelOptions {
   internalChannelParams?: {
     forwardChannelRequestTimeoutMs?: number;
   };
+  useFetchStreams?: boolean;
   xmlHttpFactory?: unknown;
   requestRefreshThresholds?: { [key: string]: number };
 }