Revert "Fix remaining strong-mode warnings and errors in dart:io."

sdk/lib/io/platform_impl.dart

 // Copyright (c) 2012, 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.
 
 part of dart.io;
 
 class _Platform {
   external static int _numberOfProcessors();
   external static String _pathSeparator();
   external static String _operatingSystem();
@@ skipping 21 matching lines @@
   external static String _packageConfig();
   external static String _version();
 
   static String executable = _executable();
   static String resolvedExecutable = _resolvedExecutable();
   static String packageRoot = _packageRoot();
   static String packageConfig = _packageConfig();
 
   // Cache the OS environemnt. This can be an OSError instance if
   // retrieving the environment failed.
-  static var/*OSError|Map<String,String>*/ _environmentCache;
+  static var _environmentCache;
 
   static int get numberOfProcessors => _numberOfProcessors();
   static String get pathSeparator => _pathSeparator();
   static String get operatingSystem => _operatingSystem();
   static Uri script;
 
   static String get localHostname {
     var result = _localHostname();
     if (result is OSError) {
       throw result;
     } else {
       return result;
     }
   }
 
   static List<String> get executableArguments => _executableArguments();
 
   static Map<String, String> get environment {
     if (_environmentCache == null) {
       var env = _environment();
       if (env is !OSError) {
         var isWindows = operatingSystem == 'windows';
-        var result = isWindows
-            ? new _CaseInsensitiveStringMap<String>()
-            : new Map<String, String>();
+        var result = isWindows ? new _CaseInsensitiveStringMap() : new Map();
         for (var str in env) {
           // The Strings returned by [_environment()] are expected to be
           // valid environment entries, but exceptions have been seen
           // (e.g., an entry of just '=' has been seen on OS/X).
           // Invalid entries (lines without a '=' or with an empty name)
           // are discarded.
           var equalsIndex = str.indexOf('=');
           if (equalsIndex > 0) {
             result[str.substring(0, equalsIndex)] =
                 str.substring(equalsIndex + 1);
           }
         }
         _environmentCache = new UnmodifiableMapView<String, String>(result);
       } else {
         _environmentCache = env;
       }
     }
 
     if (_environmentCache is OSError) {
       throw _environmentCache;
     } else {
-      return _environmentCache as Object/*=Map<String, String>*/;
+      return _environmentCache;
     }
   }
 
   static String get version => _version();
 }
 
 // Environment variables are case-insensitive on Windows. In order
 // to reflect that we use a case-insensitive string map on Windows.
 class _CaseInsensitiveStringMap<V> implements Map<String, V> {
   final Map<String, V> _map = new Map<String, V>();
 
   bool containsKey(Object key) =>
       key is String && _map.containsKey(key.toUpperCase());
   bool containsValue(Object value) => _map.containsValue(value);
   V operator [](Object key) => key is String ? _map[key.toUpperCase()] : null;
   void operator []=(String key, V value) {
     _map[key.toUpperCase()] = value;
   }
   V putIfAbsent(String key, V ifAbsent()) {
     return _map.putIfAbsent(key.toUpperCase(), ifAbsent);
   }
-  void addAll(Map<String, V> other) {
+  void addAll(Map other) {
     other.forEach((key, value) => this[key.toUpperCase()] = value);
   }
   V remove(Object key) => key is String ? _map.remove(key.toUpperCase()) : null;
   void clear() { _map.clear(); }
   void forEach(void f(String key, V value)) { _map.forEach(f); }
   Iterable<String> get keys => _map.keys;
   Iterable<V> get values => _map.values;
   int get length => _map.length;
   bool get isEmpty => _map.isEmpty;
   bool get isNotEmpty => _map.isNotEmpty;
   String toString() => _map.toString();
 }