Drop support for old SDK and shelf versions.

lib/src/util/io.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.
 
 library test.util.io;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:mirrors';
 
 import 'package:path/path.dart' as p;
 import 'package:pub_semver/pub_semver.dart';
 
 import '../backend/operating_system.dart';
 import '../runner/application_exception.dart';
 import '../util/stream_queue.dart';
 import '../utils.dart';
 
 /// The ASCII code for a newline character.
 const _newline = 0xA;
 
 /// The ASCII code for a carriage return character.
 const _carriageReturn = 0xD;
 
 /// The root directory of the Dart SDK.
-final String sdkDir = (() {
-  // TODO(kevmoo): work-around for accessing the SDK root dartbug.com/16994
-  //
-  // Don't resolve symlinks on Windows because of issue 133. Once the TODO above
-  // is resolved, we won't have to do explicit symlink resolution anyway.
-  var path = Platform.isWindows
-      ? Platform.executable
-      : new File(Platform.executable).resolveSymbolicLinksSync();
-  return p.dirname(p.dirname(path));
-})();
+final String sdkDir = p.dirname(p.dirname(Platform.resolvedExecutable));
 
 /// The version of the Dart SDK currently in use.
 final Version _sdkVersion = new Version.parse(
     new File(p.join(sdkDir, 'version'))
         .readAsStringSync().trim());
 
 /// Returns the current operating system.
 final OperatingSystem currentOS = (() {
   var name = Platform.operatingSystem;
   var os = OperatingSystem.findByIoName(name);
@@ skipping 14 matching lines @@
 final _tempDir = Platform.environment.containsKey("_UNITTEST_TEMP_DIR")
     ? Platform.environment["_UNITTEST_TEMP_DIR"]
     : Directory.systemTemp.path;
 
 /// The path to the `lib` directory of the `test` package.
 String libDir({String packageRoot}) {
   var pathToIo = libraryPath(#test.util.io, packageRoot: packageRoot);
   return p.dirname(p.dirname(p.dirname(pathToIo)));
 }
 
-/// Returns whether the current Dart version has a fix for issue 23084.
-final bool supportsPubServe = ((){
-  // This isn't 100% accurate, since issue 23084 wasn't fixed in early 1.10 dev
-  // releases, but it's unlikely anyone will be using them.
-  // TODO(nweiz): remove this when we no longer support older Dart versions.
-  return new VersionConstraint.parse('>=1.9.2 <2.0.0').allows(_sdkVersion);
-})();
-
-/// Returns whether the current Dart version supports running isolates in
-/// checked mode.
-final bool supportsIsolateCheckedMode = (() {
-  // TODO(nweiz): remove this when we no longer support older Dart versions.
-  return new VersionConstraint.parse('>=1.11.0-dev.5.0 <2.0.0')
-      .allows(_sdkVersion);
-})();
-
 // TODO(nweiz): Make this check [stdioType] once that works within "pub run".
 /// Whether "special" strings such as Unicode characters or color escapes are
 /// safe to use.
 ///
 /// On Windows or when not printing to a terminal, only printable ASCII
 /// characters should be used.
 bool get canUseSpecialChars =>
     Platform.operatingSystem != 'windows' &&
     Platform.environment["_UNITTEST_USE_COLOR"] != "false";
 
@@ skipping 120 matching lines @@
 ///
 /// This has a built-in race condition: another process may bind this port at
 /// any time after this call has returned. If at all possible, callers should
 /// use [getUnusedPort] instead.
 Future<int> getUnsafeUnusedPort() async {
   var socket = await RawServerSocket.bind(InternetAddress.LOOPBACK_IP_V4, 0);
   var port = socket.port;
   await socket.close();
   return port;
 }