Functions for conformance of style.
function adjacent(left, right) {
        left = left || token;
        right = right || nexttoken;
        if (option.white || xmode === 'styleproperty' || xmode === 'style') {
            if (left.character !== right.from && left.line === right.line) {
                warning("Unexpected space after '{a}'.", right, left.value);
            }
        }
    }