[turbofan] Remove another ineffective optimization from the ControlReducer.

[turbofan] Remove another ineffective optimization from the ControlReducer.

The condition of a Branch or Select can never be a NumberConstant,
because the resulting graph would be invalid, so we don't need to
optimize this case. It can only ever be a tagged boolean or an untagged
bit.

Drive-by-fix: Test the interesting cases in the unit tests instead.

R=jarin@chromium.org

Committed: https://crrev.com/afc2fb26a151425fac7dd290108a1a91ff3836be
Cr-Commit-Position: refs/heads/master@{#29089}

[Benedikt Meurer, 2015-06-17 12:23:58]

Hey Jaro,

Another obvious one. Please take a look.

Thanks,
Benedikt

[Jarin, 2015-06-17 12:33:01]

lgtm

[Benedikt Meurer, 2015-06-17 12:33:33]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-06-17 12:33:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1195443004/1

[commit-bot: I haz the power, 2015-06-17 12:50:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-17 12:50:56]

Patchset 1 (id:??) landed as
https://crrev.com/afc2fb26a151425fac7dd290108a1a91ff3836be
Cr-Commit-Position: refs/heads/master@{#29089}