Move pub into sdk/lib/_internal.

utils/tests/pub/install/hosted/do_not_update_on_removed_constraints_test.dart

-// Copyright (c) 2012, 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.
-
-library pub_tests;
-
-import 'dart:io';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration("doesn't update dependencies whose constraints have been "
-      "removed", () {
-    servePackages([
-      packageMap("foo", "1.0.0", [dependencyMap("shared-dep")]),
-      packageMap("bar", "1.0.0", [dependencyMap("shared-dep", "<2.0.0")]),
-      packageMap("shared-dep", "1.0.0"),
-      packageMap("shared-dep", "2.0.0")
-    ]);
-
-    d.appDir([dependencyMap("foo"), dependencyMap("bar")]).create();
-
-    schedulePub(args: ['install'],
-        output: new RegExp(r"Dependencies installed!$"));
-
-    d.packagesDir({
-      "foo": "1.0.0",
-      "bar": "1.0.0",
-      "shared-dep": "1.0.0"
-    }).validate();
-
-    d.appDir([dependencyMap("foo")]).create();
-
-    schedulePub(args: ['install'],
-        output: new RegExp(r"Dependencies installed!$"));
-
-    d.packagesDir({
-      "foo": "1.0.0",
-      "bar": null,
-      "shared-dep": "1.0.0"
-    }).validate();
-  });
-}