Reapply "Do not directly load smi constants larger than a 16 bit..."

Reapply "Do not directly load smi constants larger than a 16 bit..."

Reapply "Do not directly load smi constants larger than a 16 bit payload on
ia32" with a bugfix.  The predicate Assembler::IsSafeSmi incorrectly
returned true for non-smis on non-ia32 platforms.

Original summary: Instead of emitting a large smi constant directly as an
immediate, xor the smi with a random 32-bit cookie at compile time, emit
code to move that into a register and then to xor the register with the
cookie.

Original codereview: https://codereview.chromium.org/48743002/

R=fschneider@google.com

Committed: https://code.google.com/p/dart/source/detail?r=29533

[Florian Schneider, 2013-10-30 11:18:24]

lgtm

[Kevin Millikin (Google), 2013-10-30 11:38:49]

Committed patchset #1 manually as r29533 (presubmit successful).