Beside blocks, do also generate loops.
Also, generalize generation of breaks such that they can happen
anywhere, even outside of a block or loop.

R=eholk@chromium.org

Change-Id: Ib2f8c75913e97f331ec105fd87fc882bc5c04864
Reviewed-on: https://chromium-review.googlesource.com/771610Reviewed-by: Eric Holk <eholk@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49392}