Only if this feature is considered critical to Apple's interests.
Major companies don't test that every detail of the product works exactly as it did last version. (Well, except Microsoft pre-Ballmer.) They test that those features that have been deemed strategically important - the ones that will cause substantial portions of the userbase to leave if they're broken, or major PR disasters - continue working. Apple probably doesn't care if Grooveshark and other HTML5 music players stop working entirely. They may not break it intentionally, but if it happens to break accidentally, fixing it is low on the priority list.
Major companies don't test that every detail of the product works exactly as it did last version. (Well, except Microsoft pre-Ballmer.) They test that those features that have been deemed strategically important - the ones that will cause substantial portions of the userbase to leave if they're broken, or major PR disasters - continue working. Apple probably doesn't care if Grooveshark and other HTML5 music players stop working entirely. They may not break it intentionally, but if it happens to break accidentally, fixing it is low on the priority list.