Switch to using pub build instead of custom build_.dart script

runtime/bin/vmservice/client/build_.dart

-// Copyright (c) 2013, 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 'package:polymer/builder.dart';
-import 'dart:io';
-
-main() {
-  lint()
-    .then((_) => deploy()).then(compileToJs);
-}
-
-String findDart2JS() {
-  var dartPath = Platform.executable;
-  var lastIndex = dartPath.lastIndexOf(Platform.pathSeparator);
-  if (lastIndex != -1) {
-    var binPath = dartPath.substring(0, lastIndex);
-    return '$binPath${Platform.pathSeparator}dart2js';
-  }
-  return 'dart2js';
-}
-
-void runDart2JS(String input, String output) {
-  var dart2js_path = findDart2JS();
-  var result =
-    Process.runSync(dart2js_path,
-        [ '--minify', '-o', output, input], runInShell: true);
-  print(result.stdout);
-  print(result.stderr);
-  if (result.exitCode != 0) {
-    print("Running dart2js failed.");
-    exit(result.exitCode);
-  }
-}
-
-compileToJs(_) {
-  print("Running dart2js");
-  runDart2JS('out/web/index.html_bootstrap.dart',
-             'out/web/index.html_bootstrap.dart.js');
-  runDart2JS('out/web/index_devtools.html_bootstrap.dart',
-             'out/web/index_devtools.html_bootstrap.dart.js');
-  print("Done");
-}