Make (Object.)observed Arrays use SafeRemoveArrayHoles during sort

R=adamk,rossberg
BUG=

Review URL: https://codereview.chromium.org/15837006

Patch from Rafael Weinstein <rafaelw@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14847 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Re-enable freezing of Object.observe changeRecords now that freezing is faster.

Review URL: https://codereview.chromium.org/15898004

Patch from Rafael Weinstein <rafaelw@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14848 ce2b1a6d-e550-0410-aec6-3dcde31c8c00