Remove the line number and file information from *all* folded frames.

test/chain_test.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 chain_test;
 
 import 'dart:async';
 
 import 'package:path/path.dart' as p;
 import 'package:stack_trace/stack_trace.dart';
@@ skipping 572 matching lines @@
             'a.dart 10:11  Bang.qux\n'
             'a.dart 10:11  Zip.zap\n'
             'b.dart 10:11  Zop.zoop')
       ]);
 
       var folded = chain.foldFrames((frame) => frame.library == 'a.dart',
           terse: true);
       expect(folded.toString(), equals(
           'dart:async    Zip.zap\n'
           'b.dart 10:11  Bang.qux\n'
-          'a.dart 10:11  Zop.zoop\n'
+          'a.dart        Zop.zoop\n'
           '===== asynchronous gap ===========================\n'
-          'a.dart 10:11  Zip.zap\n'
+          'a.dart        Zip.zap\n'
           'b.dart 10:11  Zop.zoop\n'));
     });
 
     test('eliminates completely-folded traces', () {
       var chain = new Chain([
         new Trace.parse(
             'a.dart 10:11  Foo.bar\n'
             'b.dart 10:11  Bang.qux'),
         new Trace.parse(
             'a.dart 10:11  Foo.bar\n'
@@ skipping 181 matching lines @@
 ///
 /// [callback] is expected to throw the string `"error"`.
 Future<Chain> captureFuture(callback()) {
   var completer = new Completer<Chain>();
   Chain.capture(callback, onError: (error, chain) {
     expect(error, equals('error'));
     completer.complete(chain);
   });
   return completer.future;
 }