CrOS: Don't mark master builders as experimental.
CrOS: Don't mark master builders as experimental.

BUG=chromium:469346
TEST=local
  - Started master locally, "Canary Master" is no longer experimental.

R=iannucci@chromium.org

Review URL: https://codereview.chromium.org/1027963002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@294524 0039d316-1c4b-4281-b951-d872f2087c98

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