Pass an Isolate to v8::VisitHandlesWithClassIds

The Isolate version of v8::VisitHandlesWithClassIds is needed
for https://codereview.chromium.org/651713002/

R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/664473002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24671 ce2b1a6d-e550-0410-aec6-3dcde31c8c00