Array.prototype.find
Array.prototype.findIndex

http://people.mozilla.org/~jorendorff/es6-draft.html

BUG=v8:2776,v8:2777
TEST=mjsunit/harmony/array-find,mjsunit/harmony/array-findindex
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/21079003

Patch from Ioseb Dzmanashvili <ioseb.dzmanashvili@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16025 ce2b1a6d-e550-0410-aec6-3dcde31c8c00