The property details of a LookupIterator are not accessible,
if the iterator state is interceptor. Instead, use the
property attributes.

Fixes a crash in Node.js tests in Debug mode, see
https://github.com/nodejs/node/commit/c2c6ae52eaf302da9c106699b69d17c083ced316

BUG=

Review-Url: https://codereview.chromium.org/2675993002
Cr-Commit-Position: refs/heads/master@{#42941}