Implement flooring division by a constant via truncating division by a constant.

Implement flooring division by a constant via truncating division by a constant.

R=bmeurer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=20123

[Sven Panne, 2014-03-19 14:49:34]

In the current state of the CL, the Intel platforms use code with branches,
while the ARM platforms use branch-free code. I have the slight feeling that
using branches on ARM/A64 will be better, too, because the platform ports would
be more similar then and the branch-free code is quite a brain-teaser and hard
to understand and maintain. WDYT?

[Sven Panne, 2014-03-20 10:19:48]

Massaged the CL, so all platforms use simple code with branches. PTAL...

[Benedikt Meurer, 2014-03-20 12:35:38]

LGTM

[Sven Panne, 2014-03-20 13:10:36]

Committed patchset #3 manually as r20123 (presubmit successful).