Test to make sure removing a media element's <source>(s) does not cause a crash.

Removing all <source> elements with removeChild()
-> removeChild(0)
-> removeChild(1)
-> removeChild(2)
-> removeChild(3)
-> removeChild(4)
-> removeChild(5)
-> removeChild(6)
-> removeChild(7)
-> removeChild(8)
-> removeChild(9)

Removing all <source> by setting .innerHTML
-> video.innerHTML = ''

Removing all <source> elements with replaceChild()
-> replaceChild(0)
-> replaceChild(1)
-> replaceChild(2)
-> replaceChild(3)
-> replaceChild(4)
-> replaceChild(5)
-> replaceChild(6)
-> replaceChild(7)
-> replaceChild(8)
-> replaceChild(9)

PASS: A crash did not occur when removing <source> elements.

END OF TEST

