Make tests compatible with QUnit 2
- Avoid QUnit.asyncTest, QUnit.start/stop (deprecated in 1.x, removed in 2.0). Instead, use assert.async(), or return a Promise to QUnit.test().
- Remove testCount from QUnit.test(). This has not been required in QUnit for a while. MW's testrunner has also removed enforcement. QUnit's improve async control and context-aware assert tracking has been it mostly redundant. For now, keep it in most places by using assert.expect(), and remove it from simple cases.