Fixed the OS check in the SCons build. Moved SetEnvironment to platform file as Windows does not have setenv. Added the d8-windows.cc to the Visual Studio project.
Review URL: http://codereview.chromium.org/57050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1649 ce2b1a6d-e550-0410-aec6-3dcde31c8c00