Harmony: implement Math.cbrt, Math.expm1 and Math.log1p.

BUG=v8:2938
LOG=N
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/163563003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19486 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Harmony: optimize Math.clz32.

R=svenpanne@chromium.org
BUG=v8:2938
LOG=N

Review URL: https://codereview.chromium.org/172133003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19487 ce2b1a6d-e550-0410-aec6-3dcde31c8c00