[ <color> | <repeat-line-color> ]
    test_valid_value(property, "red");
    test_valid_value(property, "repeat(4, cyan)");

    // <line-color-list> = [ <line-color-or-repeat> ]+
    test_valid_value(property, "green blue");
    test_valid_value(property, "red blue green yellow pink");
    test_valid_value(property, "repeat(3, blue) repeat(4, red)");
    test_valid_value(property, "red repeat(3, blue) blue repeat(4, red green cyan)");
    test_valid_value(property, "repeat(4, red green cyan) repeat(5, yell