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
Review URL: https://codereview.chromium.org/24989003
Patch from Ross McIlroy <rmcilroy@chromium.org>.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16983 ce2b1a6d-e550-0410-aec6-3dcde31c8c00