counting the reference to the return value and passing it to the
return label.  This requires threading it through try/catch and
try/finally.  The return value is loaded into eax more lazily than
before.

Also, perform some related refactoring of jump targets.
Review URL: http://codereview.chromium.org/56172

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1669 ce2b1a6d-e550-0410-aec6-3dcde31c8c00