Work around Windows name clobbering

TBR=dslomov@chromium.org
BUG=

Review URL: https://codereview.chromium.org/194753006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19801 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Revert "Enable concurrent sweeping."

This reverts commit r19792 for breaking ARM tests.

TBR=hpayer@chromium.org

Review URL: https://codereview.chromium.org/194553003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19802 ce2b1a6d-e550-0410-aec6-3dcde31c8c00