pkg: analysis aided cleanup
pkg: analysis aided cleanup

Removed a lot of warnings and hints when opening many pkg projects in the editor

R=gram@google.com

Review URL: https://codereview.chromium.org//22284003

git-svn-id: d21bfdc9f98bb697a501ab295d9b4211dc860b14@25831 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/path