Implement Math.ceil via Math.floor.

Implement Math.ceil via Math.floor.

This way we get all the Crankshaft goodness and avoid always going
through the runtime: Less code + even some small speedup in Kraken.

R=jkummerow@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=18072

[Jakob Kummerow, 2013-11-26 12:26:32]

LGTM. You're lucky this works out for -0 ;-)

[Sven Panne, 2013-11-26 12:29:27]

On 2013/11/26 12:26:32, Jakob wrote:
> LGTM. You're lucky this works out for -0 ;-)

That's not luck, that's the spec: ;-)

   15.8.2.6 ceil (x)
   [...]
   The value of Math.ceil(x) is the same as the value of -Math.floor(-x).

[Sven Panne, 2013-11-26 12:29:56]

Committed patchset #1 manually as r18072 (presubmit successful).