Provide a helper to generate multiple Lithium instructions for one Hydrogen instruction.

R=jkummerow@chromium.org, ulan@chromium.org

Review URL: https://codereview.chromium.org/296993002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21465 ce2b1a6d-e550-0410-aec6-3dcde31c8c00