Delete dart2js_resolver and fix some typos in README

pkg/compiler/bin/resolver.dart

-// Copyright (c) 2016, 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 'package:args/args.dart';
-import 'package:compiler/src/filenames.dart';
-
-import 'package:compiler/src/dart2js_resolver.dart';
-
-main(var argv) async {
-  var parser = new ArgParser();
-  parser.addOption('deps', abbr: 'd', allowMultiple: true);
-  parser.addOption('out', abbr: 'o');
-  parser.addOption('library-root', abbr: 'l');
-  parser.addOption('packages', abbr: 'p');
-  parser.addOption('bazel-paths', abbr: 'I', allowMultiple: true);
-  var args = parser.parse(argv);
-
-  if (args.rest.isEmpty) {
-    print('missing input files');
-    exit(1);
-  }
-
-  var inputs = args.rest
-      .map((uri) => currentDirectory.resolve(nativeToUriPath(uri)))
-      .toList();
-
-  var text = await resolve(inputs,
-      deps: args['deps'],
-      root: args['library-root'],
-      packages: args['packages'],
-      bazelSearchPaths: args['bazel-paths']);
-
-  var outFile = args['out'] ?? 'out.data';
-
-  await new File(outFile).writeAsString(text);
-}