Make cctest/test-debug pass with extensions installed

Compiling extensions during context creation triggers debug events.
Work around this by installing the event listener after creating
the context

BUG=v8:2745
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/18441005

Patch from Jochen Eisinger <jochen@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15523 ce2b1a6d-e550-0410-aec6-3dcde31c8c00