Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/run/forwards_signal_posix_test.dart

-// Copyright (c) 2015, 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.
-
-import 'dart:io';
-
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-
-const _catchableSignals = const [
-  ProcessSignal.SIGHUP,
-  ProcessSignal.SIGTERM,
-  ProcessSignal.SIGUSR1,
-  ProcessSignal.SIGUSR2,
-  ProcessSignal.SIGWINCH,
-];
-
-const SCRIPT = """
-import 'dart:io';
-
-main() {
-  ProcessSignal.SIGHUP.watch().first.then(print);
-  ProcessSignal.SIGTERM.watch().first.then(print);
-  ProcessSignal.SIGUSR1.watch().first.then(print);
-  ProcessSignal.SIGUSR2.watch().first.then(print);
-  ProcessSignal.SIGWINCH.watch().first.then(print);
-
-  print("ready");
-}
-""";
-
-main() {
-  initConfig();
-  integration('forwards signals to the inner script', () {
-    d.dir(appPath, [
-      d.appPubspec(),
-      d.dir("bin", [
-        d.file("script.dart", SCRIPT)
-      ])
-    ]).create();
-
-    var pub = pubRun(args: ["bin/script"]);
-
-    pub.stdout.expect("ready");
-    for (var signal in _catchableSignals) {
-      pub.signal(signal);
-      pub.stdout.expect(signal.toString());
-    }
-
-    pub.kill();
-  });
-}