Revert "Rename internal library dart:_collection-dev to dart:_internal."

sdk/lib/_collection_dev/symbol.dart

Index: sdk/lib/_collection_dev/symbol.dart
diff --git a/sdk/lib/_collection_dev/symbol.dart b/sdk/lib/_collection_dev/symbol.dart
deleted file mode 100644
index 87517bad2b25bdfed13cc5cd954e7bff6244300a..0000000000000000000000000000000000000000
--- a/sdk/lib/_collection_dev/symbol.dart
+++ /dev/null
@@ -1,77 +0,0 @@
-// 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.
-
-part of dart._collection.dev;
-
-/**
- * Implementation of [core.Symbol].  This class uses the same name as
- * a core class so a user can't tell the difference.
- *
- * The purpose of this class is to hide [_name] from user code, but
- * make it accessible to Dart platform code via the static method
- * [getName].
- */
-class Symbol implements core.Symbol {
-  final String _name;
-
-  static final RegExp validationPattern =
-      new RegExp(r'^(?:[a-zA-Z$][a-zA-Z$0-9_]*\.)*(?:[a-zA-Z$][a-zA-Z$0-9_]*=?|'
-                 r'-|'
-                 r'unary-|'
-                 r'\[\]=|'
-                 r'~|'
-                 r'==|'
-                 r'\[\]|'
-                 r'\*|'
-                 r'/|'
-                 r'%|'
-                 r'~/|'
-                 r'\+|'
-                 r'<<|'
-                 r'>>|'
-                 r'>=|'
-                 r'>|'
-                 r'<=|'
-                 r'<|'
-                 r'&|'
-                 r'\^|'
-                 r'\|'
-                 r')$');
-
-  external const Symbol(String name);
-
-  /**
-   * Platform-private method used by the mirror system to create
-   * otherwise invalid names.
-   */
-  const Symbol.unvalidated(this._name);
-
-  // This is called by dart2js.
-  Symbol.validated(String name)
-      : this._name = validate(name);
-
-  bool operator ==(other) => other is Symbol && _name == other._name;
-
-  int get hashCode {
-    const arbitraryPrime = 664597;
-    return 0x1fffffff & (arbitraryPrime * _name.hashCode);
-  }
-
-  toString() => 'Symbol("$_name")';
-
-  /// Platform-private accessor which cannot be called from user libraries.
-  static String getName(Symbol symbol) => symbol._name;
-
-  static String validate(String name) {
-    if (name.isEmpty) return name;
-    if (name.startsWith('_')) {
-      throw new ArgumentError('"$name" is a private identifier');
-    }
-    if (!validationPattern.hasMatch(name)) {
-      throw new ArgumentError(
-          '"$name" is not an identifier or an empty String');
-    }
-    return name;
-  }
-}