Upgrade Number constructor to ES6.

Upgrade Number constructor to ES6.

Add missing constants, predicates and functions to the Number
constructor to have it offer what ES6 now specifies.

That is, extend it with:

 * isInteger(), isSafeInteger()
 * parseInt(), parseFloat()
 * EPSILON, MIN_SAFE_INTEGER, MAX_SAFE_INTEGER

LOG=N
R=mstarzinger@chromium.org
BUG=v8:3082

Review URL: https://codereview.chromium.org/124573002

Patch from Sigbjorn Finne <sigbjornf@opera.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18480 ce2b1a6d-e550-0410-aec6-3dcde31c8c00