function customNumberHandler(prefix, number, suffix)
        {
            if (number !== 0 && !suffix.length && WebInspector.CSSMetadata.isLengthProperty(this._treeElement.property.name))
                suffix = "px";
            return prefix + number + suffix;
        }
@param {string} prefix
@param {number} number
@param {string} suffix
@return {string}
@this {WebInspector.StylesSidebarPane.CSSPropertyPrompt}