Allow compile steps that don't abort.
Allow compile steps that don't abort.

I can use this usefully on FYI waterfalls that are watching the state of
a build as it progresses towards readiness.

R=stip@chromium.org
BUG=305796
TEST=local run

Review URL: https://codereview.chromium.org/61473002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@234677 0039d316-1c4b-4281-b951-d872f2087c98

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