This test checks that EventHandler attributes only accept JS functions as input.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".

PASS div.onkeydown is null
PASS div.onkeydown = callback did not throw exception.
PASS div.onkeydown is callback
PASS callbackCount is 0
PASS callbackCount is 1
PASS div.onkeydown is not null
PASS div.onkeydown = o did not throw exception.
PASS div.onkeydown is o
PASS callbackCount is 1
PASS div.onkeydown = callback did not throw exception.
PASS div.onkeydown is callback
PASS div.onkeydown = "non-object" did not throw exception.
PASS div.onkeydown is null
PASS div.onkeydown = callback did not throw exception.
PASS div.onkeydown is callback
PASS div.onkeydown = null did not throw exception.
PASS div.onkeydown is null
PASS successfullyParsed is true

TEST COMPLETE