Handle special characters in path<->uri conversion.

pkg/path/test/windows_test.dart

 // Copyright (c) 2012, 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.test.windows_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:path/path.dart' as path;
 
 main() {
@@ skipping 485 matching lines @@
     expect(builder.fromUri(Uri.parse('file://hostname/')), r'\\hostname\');
     expect(builder.fromUri(Uri.parse('foo/bar')), r'foo\bar');
     expect(builder.fromUri(Uri.parse('/C:/path/to/foo')), r'C:\path\to\foo');
     expect(builder.fromUri(Uri.parse('///C:/path/to/foo')), r'C:\path\to\foo');
     expect(builder.fromUri(Uri.parse('//hostname/path/to/foo')),
         r'\\hostname\path\to\foo');
     expect(builder.fromUri(Uri.parse('file:///C:/path/to/foo%23bar')),
         r'C:\path\to\foo#bar');
     expect(builder.fromUri(Uri.parse('file://hostname/path/to/foo%23bar')),
         r'\\hostname\path\to\foo#bar');
+    expect(builder.fromUri(Uri.parse('_%7B_%7D_%60_%5E_%20_%22_%25_')),
+        r'_{_}_`_^_ _"_%_');
     expect(() => builder.fromUri(Uri.parse('http://dartlang.org')),
         throwsArgumentError);
   });
 
   test('toUri', () {
     expect(builder.toUri(r'C:\path\to\foo'),
         Uri.parse('file:///C:/path/to/foo'));
     expect(builder.toUri(r'C:\path\to\foo\'),
         Uri.parse('file:///C:/path/to/foo/'));
     expect(builder.toUri(r'C:\'), Uri.parse('file:///C:/'));
     expect(builder.toUri(r'\\hostname\'), Uri.parse('file://hostname/'));
     expect(builder.toUri(r'foo\bar'), Uri.parse('foo/bar'));
     expect(builder.toUri(r'C:\path\to\foo#bar'),
         Uri.parse('file:///C:/path/to/foo%23bar'));
     expect(builder.toUri(r'\\hostname\path\to\foo#bar'),
         Uri.parse('file://hostname/path/to/foo%23bar'));
+    expect(builder.toUri(r'C:\_{_}_`_^_ _"_%_'),
+        Uri.parse('file:///C:/_%7B_%7D_%60_%5E_%20_%22_%25_'));
+    expect(builder.toUri(r'_{_}_`_^_ _"_%_'),
+        Uri.parse('_%7B_%7D_%60_%5E_%20_%22_%25_'));
   });
 }