Fix native extensions located in packages on Windows.

runtime/bin/builtin.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 builtin;
 import 'dart:io';
 import 'dart:async';
 // import 'root_library'; happens here from C Code
 
 // The root library (aka the script) is imported into this library. The
@@ skipping 198 matching lines @@
 String _resolveUri(String base, String userString) {
   var baseUri = Uri.parse(base);
   _logResolution('# Resolving: $userString from $base');
 
   var uri = Uri.parse(userString);
   var resolved;
   if ('dart-ext' == uri.scheme) {
     // Relative URIs with scheme dart-ext should be resolved as if with no
     // scheme.
     resolved = baseUri.resolve(uri.path);
-    var path = resolved.path;
     if (resolved.scheme == 'package') {
       // If we are resolving relative to a package URI we go directly to the
       // file path and keep the dart-ext scheme. Otherwise, we will lose the
       // package URI path part.
-      path = _filePathFromPackageUri(resolved);
+      resolved = new Uri.file(_filePathFromPackageUri(resolved));

[kustermann, 2014/01/28 21:58:38]

I thought you can have package roots which are HTTP urls. Which means, that you
would need to fetch the .so/.dll file and store it in a temporary place and load
it then.

If you can have HTTP urls as package-roots then this is broken!

[Bill Hesse, 2014/01/28 22:55:40]

Yes.  It was also broken earlier, but I have changed the CL to include a check.

     }
-    resolved = new Uri(scheme: 'dart-ext', path: path);
+    resolved = new Uri(scheme: 'dart-ext', path: resolved.path);
   } else {
     resolved = baseUri.resolve(userString);
   }
   _logResolution('# Resolved to: $resolved');
   return resolved.toString();
 }
 
 
 // Returns either a file path or a URI starting with http:, as a String.
 String _filePathFromUri(String userUri) {
@@ skipping 35 matching lines @@
 
     throw "URIs using the 'package:' scheme should look like "
           "'$right', not '$wrong'.";
   }
 
   var packageRoot = _packageRoot == null ?
                     _entryPointScript.resolve('packages/') :
                     _packageRoot;
   return _filePathFromUri(packageRoot.resolve(uri.path).toString());
 }