Don't throw for unparseable frames.

lib/src/unparsed_frame.dart

Index: lib/src/unparsed_frame.dart
diff --git a/lib/src/unparsed_frame.dart b/lib/src/unparsed_frame.dart
new file mode 100644
index 0000000000000000000000000000000000000000..19d09c65ffc580a9f74c0a4cafb5f615ba37a3ee
--- /dev/null
+++ b/lib/src/unparsed_frame.dart
@@ -0,0 +1,26 @@
+// 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;
+  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;
+}