Fix other HttpRequest implementations.
Fix other HttpRequest implementations.

BUG=

Review URL: https://codereview.chromium.org//131213002

git-svn-id: a0fc6a377c96b9059f80895148836233a16d98be@31648 260f80e4-7a28-3924-810f-c04153c831b5

kasperpeulen/http,dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http,dart-lang/http,donny-dont/http,dart-lang/http,dart-lang/http,dart-lang/http