allowing the value of the rightmost subexpressions to be evaluated
into an accumulator register (eg, eax, rax, or r0) rather than onto
the stack.

Review URL: http://codereview.chromium.org/541047

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3630 ce2b1a6d-e550-0410-aec6-3dcde31c8c00