Lint to prefer x.isNotEmpty vs. !x.isEmpty (#143).

lib/src/sdk.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 linter.src.sdk;
 
 import 'package:analyzer/file_system/file_system.dart' as resource;
 import 'package:analyzer/file_system/memory_file_system.dart' as resource;
 import 'package:analyzer/src/context/cache.dart'
     show AnalysisCache, CachePartition;
@@ skipping 74 matching lines @@
 const Object deprecated = const Deprecated("next release");
 
 class Iterator<E> {
   bool moveNext();
   E get current;
 }
 
 abstract class Iterable<E> {
   Iterator<E> get iterator;
   bool get isEmpty;
+  bool get isNotEmpty;
 }
 
 abstract class List<E> implements Iterable<E> {
   void add(E value);
   E operator [](int index);
   void operator []=(int index, E value);
   Iterator<E> get iterator => null;
   void clear();
+  bool get isEmpty;
+  bool get isNotEmpty;
 }
 
 abstract class Map<K, V> extends Object {
   Iterable<K> get keys;
+  bool get isEmpty;
+  bool get isNotEmpty;
 }
 
 external bool identical(Object a, Object b);
 
 void print(Object object) {}
 
 class _Override {
   const _Override();
 }
 const Object override = const _Override();
@@ skipping 295 matching lines @@
   @override
   AnalysisCache createCacheFromSourceFactory(SourceFactory factory) {
     if (factory == null) {
       return super.createCacheFromSourceFactory(factory);
     }
     return new AnalysisCache(<CachePartition>[
       AnalysisEngine.instance.partitionManager_new.forSdk(sdk)
     ]);
   }
 }