build: Update qunitjs to 2.9.1
Code and integrity from <https://code.jquery.com/qunit/>.
Release notes at <https://github.com/qunitjs/qunit/releases>.
Highlights for the browser version:
- [2.7.0] Reporter: Remove cost of DOM size when
using "hidepassed=true".
- [2.7.0] Reporter: Use perf.now() for improved accurracy
of unit test durations.
- [2.7.0] Reporter: Make debugging tests in a browser
easier by adding timeline markers for DevTools.
Highlights for the npm package / CLI version:
- [2.9.0] CLI: Reduce dependency tree size
from 143 packages to 9 packages.
Change-Id: I38408d90765cd18d5dd6952b8b6b30cbfa0c7ed5