Fix platform-cygwin.cc to really not use an Isolate
Fix platform-cygwin.cc to really not use an Isolate

BUG=none
R=jkummerow@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/367953002

git-svn-id: f98b9d40cb02301bc76fa9e1b46ee668158567fd@22152 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh