Add tests for generator/debugger interaction

R=yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/247003004


Review URL: https://codereview.chromium.org/256733004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20964 ce2b1a6d-e550-0410-aec6-3dcde31c8c00