Fix error in processing dart-ext urls with a relative path.

runtime/bin/builtin.dart

Index: runtime/bin/builtin.dart
diff --git a/runtime/bin/builtin.dart b/runtime/bin/builtin.dart
index 51e6dce17b8ec0c6c061b0e8a49aa8ba67752497..cb3691aa8d7763703b4d5fe4f0177b70de113c1c 100644
--- a/runtime/bin/builtin.dart
+++ b/runtime/bin/builtin.dart
@@ -244,7 +244,9 @@ String _filePathFromUri(String userUri) {
       return uri.toFilePath();
       break;
     case 'dart-ext':

[Søren Gjesse, 2014/01/27 20:57:51]

This should just be

  new Uri.file(uri.path)

that should take care of the relative/absolute path.

Also shouldn't we check that the host is empty? Don't think we want to load
extensions from a file server.

-      return new Uri(scheme: 'file',
+      // Relative file URIs don't start with file:///.
+      var scheme = (uri.path.startsWith('/') ? 'file' : '');
+      return new Uri(scheme: scheme,
                      host: uri.host,
                      path: uri.path).toFilePath();
       break;