ARM: Load undefined receiver sentinel without constant pool

ARM: Load undefined receiver sentinel without constant pool

Each call to emit_32 uses 5 constant pool slots:
* the "emit_32" string
* undefined (the receiver)
* the argument (heap number)
* the load IC
* the call IC

This change cuts that down 20% to 4, by loading the undefined from the heap roots.

R=verwaest@chromium.org
BUG=

Committed: https://crrev.com/a820568b1ffbf76c3f80b9e00fc0b988b073dfaf
Cr-Commit-Position: refs/heads/master@{#26979}

[Erik Corry Chromium.org, 2015-03-04 09:40:18]

PTAL

[Toon Verwaest, 2015-03-04 10:01:11]

Lgtm. The heap number should also already be converted to a SMI in most cases,
so your % is even higher ;-)

[Erik Corry Chromium.org, 2015-03-04 10:06:56]

The CQ bit was checked by erikcorry@chromium.org

[commit-bot: I haz the power, 2015-03-04 10:07:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/980563002/1

[commit-bot: I haz the power, 2015-03-04 11:02:26]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-04 11:02:33]

Patchset 1 (id:??) landed as
https://crrev.com/a820568b1ffbf76c3f80b9e00fc0b988b073dfaf
Cr-Commit-Position: refs/heads/master@{#26979}