Revert "Don't use `LinkedList` in the core libraries anymore."

sdk/lib/internal/internal.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.
 
 library dart._internal;
 
 import 'dart:collection';
 
 import 'dart:core' hide Symbol;
 import 'dart:core' as core;
 import 'dart:math' show Random;
 
 part 'iterable.dart';
 part 'list.dart';
 part 'print.dart';
 part 'sort.dart';
 part 'symbol.dart';
-part 'linked_list.dart';
 
 // Powers of 10 up to 10^22 are representable as doubles.
 // Powers of 10 above that are only approximate due to lack of precission.
 // Used by double-parsing.
 const POWERS_OF_TEN = const [
   1.0, // 0
   10.0,
   100.0,
   1000.0,
   10000.0,
@@ skipping 60 matching lines @@
 
 /// Parses two hex digits in a string.
 ///
 /// Returns a negative value if either digit isn't valid.
 int parseHexByte(String source, int index) {
   assert(index + 2 <= source.length);
   int digit1 = hexDigitValue(source.codeUnitAt(index));
   int digit2 = hexDigitValue(source.codeUnitAt(index + 1));
   return digit1 * 16 + digit2 - (digit2 & 256);
 }