VirtualAlloc on Windows 7 does not currently provide sufficient randomization to protect JIT code from being aligned in large regions at a predictable location.

This patch manually randomizes the allocation address for PAGE_EXECUTE_READWRITE regions between kAllocationRandomAddressMin and kAllocationRandomAddressMax.

BUG=none
TEST=allocate lots of javascript code and check for contiguous allocations

Patch by Paul Mehta <pmehta@chromium.org>

Review URL: http://codereview.chromium.org/2832095


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5169 ce2b1a6d-e550-0410-aec6-3dcde31c8c00