remove Isolate::Current from most files starting with 'o' through 'r'

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/23757017

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16513 ce2b1a6d-e550-0410-aec6-3dcde31c8c00