build: Test the 'minify' task in CI
build: Test the 'minify' task in CI

Using the same hack for VisualEditor, which avoids slowing down developers
whilst maintaining integrity of the repo.

Change-Id: I40fcdb075db0ee0664598e1b396431c66077b702

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui