How to use the css-tree.lexer.matchDeclaration function in css-tree

module.exports = function compressPercentage(node, item) {
    node.value = packNumber(node.value, item);

    if (node.value === '0' && this.declaration && !blacklist.has(this.declaration.property)) {
        // try to convert a number
        item.data = {
            type: 'Number',
            loc: node.loc,
            value: node.value
        };

        // that's ok only when new value matches on length
        if (!lexer.matchDeclaration(this.declaration).isType(item.data, 'length')) {
            // otherwise rollback changes
            item.data = node;
        }
    }
};

function compressIdent(node, item) {
    if (this.declaration === null) {
        return;
    }

    var color = node.name.toLowerCase();

    if (NAME_TO_HEX.hasOwnProperty(color) &&
        lexer.matchDeclaration(this.declaration).isType(node, 'color')) {
        var hex = NAME_TO_HEX[color];

        if (hex.length + 1 <= color.length) {
            // replace for shorter hex value
            item.data = {
                type: 'HexColor',
                loc: node.loc,
                value: hex
            };
        } else {
            // special case for consistent colors
            if (color === 'grey') {
                color = 'gray';
            }

            // just replace value for lower cased name