It would be useful to be able to annotate a particular test so it will only run when driven by a particular set of browsers.

Some sample use cases:

1. Some tests cannot target the incomplete js impl found in html unit. I would mark such tests not to run when htmlunit is the configured browser (in CI for instance)
2. Some tests may target non-standard behaviour in certain browsers (older IE versions for instance) and may not make sense to run in all browsers. I would mark such tests not to run only when IE is the configured browser.