Version 3.28.71.14 (merged r23144)

Correctly handle holes when concat()ing double arrays

BUG=chromium:403409
LOG=N
TBR=hpayer@chromium.org

Review URL: https://codereview.chromium.org/608373002

git-svn-id: https://v8.googlecode.com/svn/branches/3.28@24296 ce2b1a6d-e550-0410-aec6-3dcde31c8c00