Re-land "Add methods to enable configuration of ResourceConstraints based on limits derived at..."

Re-land "Add methods to enable configuration of ResourceConstraints based on limits derived at runtime."

Adds ConfigureResourceConstraintsForCurrentPlatform and SetDefaultResourceConstraintsForCurrentPlatform which configure the heap based on the available physical memory, rather than hard-coding by platform as previous. This change also adds OS::TotalPhysicalMemory to platform.h.

The re-land fix the performance regression caused by accidental change in default max young space size.

BUG=292928
R=hpayer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=16983

[Hannes Payer (out of office), 2013-09-27 10:45:51]

LGTM

[Hannes Payer (out of office), 2013-09-27 10:53:23]

Committed patchset #2 manually as r16983 (presubmit successful).