Avoid brittle use of .bind in Promise.all

R=yangguo@chromium.org
BUG=v8:3420
LOG=Y

Review URL: https://codereview.chromium.org/366103005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22231 ce2b1a6d-e550-0410-aec6-3dcde31c8c00