GitLab

 - Extracted BisectPrinter, which contains everything related to printing
 - Extracted BisectState and RevisionState, which represent bisect-in-progress
 - Rewrote BisectResults - in particular split up GetRevisionDict, which is now its constructor
 - Added tests for BisectResults, fixed bugs in _FindOtherRegressions
 - Added tests for BisectState

R=qyearsley@chromium.org

Review URL: https://codereview.chromium.org/664753002

Cr-Commit-Position: refs/heads/master@{#300677}