every test.
add_result_callback(function(){
    target.attributeStyleMap.clear();
    // Clears 'div' rule in #style:
    style.sheet.rules[0].styleMap.clear();
});

// In the following utility functions, the 'map' parameter (if present)
// can be any StylePropertyMap. (Not StylePropertyMapReadOnly).

// Verifies that get()/getAll() reifies the specified property to a
// CSSUnparsedValue, with a string serialization equal to 'value'.
function verify_map_get_unparsed(map, name, value) {
    map.set(name, val