Make annotator print_step use the annotation stream
Make annotator print_step use the annotation stream

This will prevent unfortunate logs where the step outputs so much stderr (such
as repo sync steps) that the 'preamble' of the step gets pushed all the way to
the bottom of the log.

R=stip@chromium.org

Review URL: https://codereview.chromium.org/27510011

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@229269 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build