Handle possible difference between function code and activated code on preparation...

Handle possible difference between function code and activated code on preparation for break points

The full code activated for a function might not be the same code as
is currently the active full code for a function. There where some
asumptions in the debugger preparation for break points.

Unfortunately there is currently no regression test.

R=jkummerow@chromium.org

BUG=
TEST=

Review URL: http://codereview.chromium.org//8818010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10176 ce2b1a6d-e550-0410-aec6-3dcde31c8c00