This introduces additional verification logic to ensure that the
condition passed to Branch/Select operators is always of type
Boolean.

CQ_INCLUDE_TRYBOTS=master.tryserver.v8:v8_win64_dbg
TBR=jarin@chromium.org
BUG=v8:5267

Review-Url: https://codereview.chromium.org/2672713002
Cr-Commit-Position: refs/heads/master@{#42875}