The heavy version is for x86 and x64.  The light version
is for ARM and MIPS.  Remove the elements_ array from the
virtual frame in the light version.  More simplifications
to come, followed by light register allocation.
Review URL: http://codereview.chromium.org/1164002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4272 ce2b1a6d-e550-0410-aec6-3dcde31c8c00