With the new JS test framework, we had experimented with an autodestroy
feature, meaning that all views/widgets are automatically destroyed
after a while. By default, it was 50ms, because we could not hook some
code to run after the end of the current test.
For various reasons, this was not a good idea: some side effects, such
as modifications of the session or of the DOM (with modals) could
interfere with other tests. This commit disable the feature.
From now on, we will have to destroy each widgets created in a test.