Second round of cleanups for new optional parameter semantics. Review URL: https://codereview.chromium.org//11194025
Second round of cleanups for new optional parameter semantics.
Review URL: https://codereview.chromium.org//11194025

git-svn-id: 965eb99b257a0350f91a5ab8607b3dea57271703@13759 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/args,iansf/args,ronlobo/args,seaneagan/args