Revert "Move the linter core to the analyzer package"

pkg/analyzer/lib/src/lint/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.
-
-import 'dart:io';
-
-import 'package:analyzer/src/lint/util.dart';
-import 'package:glob/glob.dart';
-import 'package:path/path.dart' as p;
-
-final dartMatcher = new Glob('**.dart');
-
-/// Shared IO sink for standard error reporting.
-/// Visible for testing
-IOSink errorSink = stderr;
-
-/// Shared IO sink for standard out reporting.
-/// Visible for testing
-IOSink outSink = stdout;
-
-/// Cached project package.
-String _projectPackageName;
-
-/// Cached project root.
-String _projectRoot;
-
-/// Collect all lintable files, recursively, under this [path] root, ignoring
-/// links.
-Iterable<File> collectFiles(String path) {
-  List<File> files = [];
-
-  var file = new File(path);
-  if (file.existsSync()) {
-    files.add(file);
-  } else {
-    var directory = new Directory(path);
-    if (directory.existsSync()) {
-      for (var entry
-          in directory.listSync(recursive: true, followLinks: false)) {
-        var relative = p.relative(entry.path, from: directory.path);
-
-        if (isLintable(entry) && !isInHiddenDir(relative)) {
-          files.add(entry);
-        }
-      }
-    }
-  }
-
-  return files;
-}
-
-/// Returns `true` if this [entry] is a Dart file.
-bool isDartFile(FileSystemEntity entry) => isDartFileName(entry.path);
-
-/// Returns `true` if this relative path is a hidden directory.
-bool isInHiddenDir(String relative) =>
-    p.split(relative).any((part) => part.startsWith("."));
-
-/// Returns `true` if this relative path is a hidden directory.
-bool isLintable(FileSystemEntity file) =>
-    file is File && (isDartFile(file) || isPubspecFile(file));
-
-/// Returns `true` if this [entry] is a pubspec file.
-bool isPubspecFile(FileSystemEntity entry) =>
-    isPubspecFileName(p.basename(entry.path));
-
-/// Synchronously read the contents of the file at the given [path] as a string.
-String readFile(String path) => new File(path).readAsStringSync();