[x64] Fix handling of Smi constants in LSubI and LBitI

[x64] Fix handling of Smi constants in LSubI and LBitI

Smi immediates are not supported, so instructions with Smi representations need their constants in a register. LAddI has already been doing this. The manifestation of the bug was that an operation would compute 0 instead of the correct result.

BUG=chromium:478612
LOG=y
R=verwaest@chromium.org

Committed: https://crrev.com/5379d8bc36b3388df4f5a6f7e0a86168f1a5ff0e
Cr-Commit-Position: refs/heads/master@{#29529}

[Jakob Kummerow, 2015-07-07 13:02:49]

PTAL.

[Toon Verwaest, 2015-07-08 09:56:24]

lgtm, thanks for fixing!

[Jakob Kummerow, 2015-07-08 09:57:00]

The CQ bit was checked by jkummerow@chromium.org

[commit-bot: I haz the power, 2015-07-08 09:57:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1224623017/1

[commit-bot: I haz the power, 2015-07-08 10:20:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-08 10:20:41]

Patchset 1 (id:??) landed as
https://crrev.com/5379d8bc36b3388df4f5a6f7e0a86168f1a5ff0e
Cr-Commit-Position: refs/heads/master@{#29529}