Remove unmodifiable map wrappers that could instead use UnmodifiableMapView.

sdk/lib/_internal/lib/js_mirrors.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.
 
 library dart._js_mirrors;
 
 import 'dart:async';
 
 import 'dart:collection' show
-    UnmodifiableListView;
+    UnmodifiableListView,
+    UnmodifiableMapView;
 
 import 'dart:mirrors';
 
 import 'dart:_foreign_helper' show
     JS,
     JS_CURRENT_ISOLATE,
     JS_CURRENT_ISOLATE_CONTEXT,
     JS_GET_NAME;
 
 import 'dart:_internal' as _symbol_dev;
@@ skipping 2807 matching lines @@
     case MISSING_CONSTRUCTOR:
       return
           "NoSuchMethodError: No constructor named '${n(_name)}' in class"
           " '${n(_cls.qualifiedName)}'.";
     default:
       return 'NoSuchMethodError';
     }
   }
 }
 
-// Copied from package "unmodifiable_collection".
-// TODO(14314): Move to dart:collection.
-class UnmodifiableMapView<K, V> implements Map<K, V> {
-  Map<K, V> _source;
-  UnmodifiableMapView(Map<K, V> source) : _source = source;
-
-  static void _throw() {
-    throw new UnsupportedError("Cannot modify an unmodifiable Map");
-  }
-
-  int get length => _source.length;
-
-  bool get isEmpty => _source.isEmpty;
-
-  bool get isNotEmpty => _source.isNotEmpty;
-
-  V operator [](K key) => _source[key];
-
-  bool containsKey(K key) => _source.containsKey(key);
-
-  bool containsValue(V value) => _source.containsValue(value);
-
-  void forEach(void f(K key, V value)) => _source.forEach(f);
-
-  Iterable<K> get keys => _source.keys;
-
-  Iterable<V> get values => _source.values;
-
-  void operator []=(K key, V value) => _throw();
-
-  V putIfAbsent(K key, V ifAbsent()) { _throw(); }
-
-  void addAll(Map<K, V> other) => _throw();
-
-  V remove(K key) { _throw(); }
-
-  void clear() => _throw();
-}
-
 Symbol getSymbol(String name, LibraryMirror library) {
   if (_isPublicSymbol(name)) {
     return new _symbol_dev.Symbol.validated(name);
   }
   if (library == null) {
     throw new ArgumentError(
         "Library required for private symbol name: $name");
   }
   if (!_symbol_dev.Symbol.isValidSymbol(name)) {
     throw new ArgumentError("Not a valid symbol name: $name");
   }
   throw new UnimplementedError(
       "MirrorSystem.getSymbol not implemented for private names");
 }
 
 bool _isPublicSymbol(String name) {
   // A symbol is public if it doesn't start with '_' and it doesn't
   // have a part (following a '.') that starts with '_'.
   const int UNDERSCORE = 0x5f;
   if (name.isEmpty) return true;
   int index = -1;
   do {
     if (name.codeUnitAt(index + 1) == UNDERSCORE) return false;
     index = name.indexOf('.', index + 1);
   } while (index >= 0 && index + 1 < name.length);
   return true;
 }