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

tests/corelib_2/reg_exp_cache_test.dart

+// Copyright (c) 2017, 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.
+
+// Runs several similar regexps in a loop to see if an internal cache works (at
+// least in easy conditions).
+
+import "package:expect/expect.dart";
+
+void main() {
+  for (int j = 1; j < 50; j++) {
+    for (int i = 0; i < 20 * j; i++) {
+      var regExp = new RegExp("foo$i");
+      var match = regExp.firstMatch("foo$i");
+      Expect.isNotNull(match);
+      Expect.equals("foo$i", match[0]);
+    }
+  }
+}