Instead of generating two instructions and combining them
at lithium translation using the EmitAtUses predicate, we
generate the correct branch instruction right from the start.
Review URL: http://codereview.chromium.org/7237024

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8495 ce2b1a6d-e550-0410-aec6-3dcde31c8c00