ToBoolean was used with conditional jumps. An earlier cl
(https://codereview.chromium.org/1426913002/) merges jumps
and ToBoolean into a single bytecode. So, we no longer need
ToBoolean bytecode.

BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1507683005

Cr-Commit-Position: refs/heads/master@{#32707}