Remove dependency from platform files on v8.h

Pass flag values in through a central initialize call.

We still depend on utils.h for RoundUp and IsAligned.

BUG=none
R=bmeurer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/353113003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22048 ce2b1a6d-e550-0410-aec6-3dcde31c8c00