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

sdk/lib/core/symbol.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.
 
 part of dart.core;
 
 /// Opaque name used by mirrors, invocations and [Function.apply].
 class Symbol {
   /**
    * Constructs a new Symbol.
    *
    * An [ArgumentError] is thrown if [name] starts with an underscore, or if
    * [name] is not a [String].  An [ArgumentError] is thrown if [name] is not
    * an empty string and is not a valid qualified identifier optionally
    * followed by [:'=':].
    *
    * The following text is non-normative:
    *
    * Creating non-const Symbol instances may result in larger output.  If
    * possible, use [MirrorsUsed] in "dart:mirrors" to specify which names might
    * be passed to this constructor.
    */
-  const factory Symbol(String name) = _collection_dev.Symbol;
+  const factory Symbol(String name) = internal.Symbol;
 }