By checking for the expected value directly we can shorten the code, and
it simplifies removing the dependencies between the tests in the next
commit (by having fewer places to change). Note that this follows the
same pattern as PRs mozilla#19192, mozilla#19001 and mozilla#18399 and also helps to remove
any further possibilities for intermittent failures.

…on tests

The integration tests are order-dependent because they rely on input
field state set by a previous test. This commit fixes the issue by
updating the values to match the initial state of the document, which
makes sure that we don't build upon values from previous tests while
still testing the intended logic in the individual tests like before.

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.