Refactor pkg/path.

pkg/path/lib/src/path_exception.dart

Index: pkg/path/lib/src/path_exception.dart
diff --git a/pkg/path/lib/src/path_exception.dart b/pkg/path/lib/src/path_exception.dart
new file mode 100644
index 0000000000000000000000000000000000000000..49bd268e4d5382de9d0bc547946a19589be409d8
--- /dev/null
+++ b/pkg/path/lib/src/path_exception.dart
@@ -0,0 +1,15 @@
+// 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 path.path_exception;
+
+/// An exception class that's thrown when a path operation is unable to be
+/// computed accurately.
+class PathException implements Exception {
+  String message;
+
+  PathException(this.message);
+
+  String toString() => "PathException: $message";
+}