src, test: fix up ObjectWrap, `make test-addons`

V8 was upgraded from 3.22 to 3.24 in commit 1c7bf24.  Upgrade source
files in test/addons/ and automatically generated tests from
doc/api/addons.markdown to the new V8 API.

This coincidentally fixes a bug in src/node_object_wrap.h where it was
still using the old V8 weak persistent handle interface, which is gone
in 3.24.

Suggested reviewer: @indutny