Make List.from and Iterable.toList default to not growable.

pkg/scheduled_test/lib/src/schedule.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 schedule;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:unittest/unittest.dart' as unittest;
@@ skipping 453 matching lines @@
   /// Returns a detailed representation of the queue as a tree of tasks. If
   /// [highlight] is passed, that task is specially highlighted.
   ///
   /// [highlight] must be a task in this queue.
   String generateTree([Task highlight]) {
     assert(highlight == null || highlight.queue == this);
     return _contents.map((task) {
       var lines = task.toString().split("\n");
       var firstLine = task == highlight ?
           "> ${lines.first}" : "* ${lines.first}";
-      lines = [firstLine]..addAll(lines.skip(1).map((line) => "| $line"));
+      lines = new List.from(lines.skip(1).map((line) => "| $line"));
+      lines.insertRange(0, 1, firstLine);
       return lines.join("\n");
     }).join("\n");
   }
 }