Remove file_util::kPathSeparator from posix.

Review URL: http://codereview.chromium.org/12489

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@6099 0039d316-1c4b-4281-b951-d872f2087c98

• base/file_path.cc[diff]
• base/file_path.h[diff]
• base/file_util.cc[diff]
• base/file_util.h[diff]
• base/file_util_linux.cc[diff]
• base/file_util_mac.mm[diff]
• base/file_util_unittest.cc[diff]
• base/file_util_win.cc[diff]
• chrome/browser/safe_browsing/safe_browsing_database_unittest.cc[diff]
• net/url_request/url_request_unittest.cc[diff]
• net/url_request/url_request_unittest.h[diff]
• webkit/glue/dom_serializer_unittest.cc[diff]
• webkit/tools/test_shell/test_shell_gtk.cc[diff]
• webkit/tools/test_shell/test_shell_mac.mm[diff]