Remove support for SDK dependencies.

utils/tests/pub/install/sdk/check_out_transitive_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 '../../test_pub.dart';
-
-main() {
-  integration('includes transitive dependencies', () {
-    dir(sdkPath, [
-      dir('pkg', [
-        dir('foo', [
-          libDir('foo', 'foo 0.1.2+3'),
-          libPubspec('foo', '0.0.0-not.used', deps: [{'sdk': 'bar'}])
-        ]),
-        dir('bar', [
-          libDir('bar', 'bar 0.1.2+3'),
-          libPubspec('bar', '0.0.0-not.used')
-        ])
-      ])
-    ]).scheduleCreate();
-
-    dir(appPath, [
-      appPubspec([{'sdk': 'foo'}])
-    ]).scheduleCreate();
-
-    schedulePub(args: ['install'],
-        output: new RegExp(r"Dependencies installed!$"));
-
-    packagesDir({
-      'foo': '0.1.2+3',
-      'bar': '0.1.2+3'
-    }).scheduleValidate();
-  });
-}