MIPS: We should never allocate a 0-sized buffer, so never grow from 0.

Port r22947 (e72b5aed) and r22944 (d1d8f44c)

BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/446923003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22948 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Update webkit test for expected own properties

Follow up to: 438103002

BUG=None
LOG=Y
R=adamk@chromium.org, rossberg@chromium.org

Review URL: https://codereview.chromium.org/439153005

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

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22949 ce2b1a6d-e550-0410-aec6-3dcde31c8c00