Function mixin

libs/echarts/echarts.simple.js:504–509

* @memberOf module:zrender/core/util * @param {Object|Function} target * @param {Object|Function} sorce * @param {boolean} overlay

(target, source, overlay)

 * @param {boolean} overlay
 */
function mixin(target, source, overlay) {
    target = 'prototype' in target ? target.prototype : target;
    source = 'prototype' in source ? source.prototype : source;

    defaults(target, source, overlay);
}

/**
 * Consider typed array.