Garden-o-matic: Cache parsed test results and add progress to test results

BUG=
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/171083004

git-svn-id: svn://svn.chromium.org/blink/trunk@167536 bbb929c8-8fbe-4397-9dbb-9b2b20218538