pkg/stack_trace: use List.unmodifiable when possible

lib/src/chain.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.
 
 import 'dart:async';
-import 'dart:collection';
 import 'dart:math' as math;
 
 import 'frame.dart';
 import 'stack_zone_specification.dart';
 import 'trace.dart';
 import 'utils.dart';
 
 /// A function that handles errors in the zone wrapped by [Chain.capture].
 @Deprecated("Will be removed in stack_trace 2.0.0.")
 typedef void ChainHandler(error, Chain chain);
@@ skipping 122 matching lines @@
   factory Chain.parse(String chain) {
     if (chain.isEmpty) return new Chain([]);
     if (!chain.contains(chainGap)) return new Chain([new Trace.parse(chain)]);
 
     return new Chain(
         chain.split(chainGap).map((trace) => new Trace.parseFriendly(trace)));
   }
 
   /// Returns a new [Chain] comprised of [traces].
   Chain(Iterable<Trace> traces)
-      : traces = new UnmodifiableListView<Trace>(traces.toList());
+      : traces = new List<Trace>.unmodifiable(traces);
 
   /// Returns a terser version of [this].
   ///
   /// This calls [Trace.terse] on every trace in [traces], and discards any
   /// trace that contain only internal frames.
   Chain get terse => foldFrames((_) => false, terse: true);
 
   /// Returns a new [Chain] based on [this] where multiple stack frames matching
   /// [predicate] are folded together.
   ///
@@ skipping 46 matching lines @@
 
     // Don't call out to [Trace.toString] here because that doesn't ensure that
     // padding is consistent across all traces.
     return traces.map((trace) {
       return trace.frames.map((frame) {
         return '${padRight(frame.location, longest)}  ${frame.member}\n';
       }).join();
     }).join(chainGap);
   }
 }