For non-builtin props, getAttribute retrieves the stringified value of the
prop. setAttribute also stringifies the value if it's a builtin only.
Signed-off-by: Gabriel Ivăncescu <gabrielopcode@gmail.com>
Signed-off-by: Jacek Caban <jacek@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>