Update oauth2's dependency on http.
Update oauth2's dependency on http.

OAuth2 was upgraded to support the new HTTP API prior to the new
conventions for package versioning, and the upgraded version hasn't
been released yet.

R=rnystrom@google.com
BUG=15809

Review URL: https://codereview.chromium.org//98163005

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@31523 260f80e4-7a28-3924-810f-c04153c831b5

dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk