generated in one-pass from the source AST, code is generated from the
CFG.  Enabled by the flag --multipass and disabled by default.

Rudimentary and currently only supports literal expressions and return
statements.  There are some other known limitations (e.g., missing
support for tracing).

Review URL: http://codereview.chromium.org/159695

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2596 ce2b1a6d-e550-0410-aec6-3dcde31c8c00