ARM: The Simulator will now handle different VFP rounding modes. RZ and RM are implemented.  This is a commit of 
http://codereview.chromium.org/4295003/show for Alexander Rames of ARM.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5790 ce2b1a6d-e550-0410-aec6-3dcde31c8c00