Don't throw for unparseable frames.

lib/src/unparsed_frame.dart

+// Copyright (c) 2015, 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 stack_trace.unparsed_frame;
+
+import 'frame.dart';
+
+/// A frame that failed to parse.
+///
+/// The [member] property contains the original frame's contents.
+class UnparsedFrame implements Frame {
+  final Uri uri = new Uri(path: "unparsed");
+  final int line = null;
+  final int column = null;

[Bob Nystrom, 2015/08/12 16:47:56]

Do users expect that these are nullable? It may be safer to return 0 or -1.

[nweiz, 2015/08/12 20:38:42]

Yes, it's clearly documented in Frame and in practice stack frames don't include
line/column info reasonably often. Also if users are expecting them to be valid,
null will fail faster than a sentinel int.

+  final bool isCore = false;
+  final String library = "unparsed";
+  final String package = null;
+  final String location = "unparsed";
+
+  final String member;
+
+  UnparsedFrame(this.member);
+
+  String toString() => _original;
+}