[turbofan] More useful typing for And, Or and Shr.

BUG=

Review URL: https://codereview.chromium.org/714413004

Cr-Commit-Position: refs/heads/master@{#25381}
[turbofan] add ForTesting to pipeline entry points that are for testing only.

R=bmeurer@chromium.org

BUG=

Review URL: https://codereview.chromium.org/727373002

Cr-Commit-Position: refs/heads/master@{#25382}