This tests if the "spellcheck" attribute is implemented as written in its specification. If this test succeeds, you can see forms filled with an invalid word "zz". Nevertheless, the "zz" is not marked as misspelled in all of them.
On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became true
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became false
zz
PASS internals.hasSpellingMarker(0, 2) became true