Fix editor warnings in http_server and mime.
Fix editor warnings in http_server and mime.

BUG=

Review URL: https://codereview.chromium.org//19158002

git-svn-id: 2cf6cc6be8bcb212571f3db34c06480b69273058@24992 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/mime