ES6: Implement Object.setPrototypeOf

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.setprototypeof

This just exposes the internal %SetPrototype and adds all the required
type checks as specified.

BUG=v8:2675
LOG=Y
R=dslomov@chromium.org, rossberg@chromium.org

Review URL: https://codereview.chromium.org/141913002

Patch from Erik Arvidsson <arv@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18685 ce2b1a6d-e550-0410-aec6-3dcde31c8c00