Only stop HTTP server if it was actually started.

Review URL: https://codereview.chromium.org//14052008

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/http@21939 260f80e4-7a28-3924-810f-c04153c831b5
1 file changed
tree: dc824f026ca074b8540113d78ae9ed9a15adea76
  1. lib/
  2. test/
  3. pubspec.yaml