Conformance tests for aborting requests

[brianquinlan]

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[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:cronet_http	1.4.0-wip	WIP (no publish necessary)
package:cupertino_http	2.2.0	already published at pub.dev
package:http	1.4.1-wip	(error) pubspec version (1.4.1-wip) and changelog (1.4.1) don't agree
package:http2	3.0.0	ready to publish	http2-v3.0.0
package:http_multi_server	3.2.2	already published at pub.dev
package:http_parser	4.1.2	already published at pub.dev
package:http_profile	0.1.1-wip	WIP (no publish necessary)
package:ok_http	0.1.1-wip	WIP (no publish necessary)
package:web_socket	1.0.1	already published at pub.dev
package:web_socket_channel	3.0.3	already published at pub.dev

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[github-actions]

PR Health

Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?

Changelog Entry ✔️

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License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

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no missing headers

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Files
pkgs/http/example/main.dart

[JaffaKetchup]

Cherry picked into #1773