Isolate the scripting integration tests

To avoid being able to introduce dependencies between tests, and to
bring existing dependencies to the surface, this commit makes sure that
we close the document between tests so that we can't accidentally rely
on state set by a previous test. This prevents multiple tests from
failing if one of them fails and makes debugging easier by being able to
run each test on their own independent of other tests.

This commit, combined with the previous ones, is enough to make the
scripting integration test suite pass consistently if random mode in
Jasmine is enabled, proving that the tests are fully isolated now.

Author: timvandermeij