to floating point and then converting back we convert directly to a
32 bit integer.  In addition the bit twiddling implementation of float-
to-integer conversion has been ported from ARM.  Testing has shown that
this runs faster than the x87 or SSE3 rounding instructions.  This change
is IA32 only.  There may be a smaller benefit from doing the same on x64.
Review URL: http://codereview.chromium.org/506052

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00