Revert "Avoid some unnecessary fast-properties map creations."

This reverts commit e1f23eab4255d63344011dfb885b8e8962cb60e2.

Broke cctest/test-heap/ReleaseOverReservedPages on a bunch of builders

http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20debug/builds/928/steps/Check/logs/ReleaseOverReservedPa..

BUG=None
LOG=N
TBR=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/709123002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25224 ce2b1a6d-e550-0410-aec6-3dcde31c8c00