Function def

static/vuejs/vue.js:375–382

* Define a property.

(obj, key, val, enumerable)

 * Define a property.
 */
function def (obj, key, val, enumerable) {
  Object.defineProperty(obj, key, {
    value: val,
    enumerable: !!enumerable,
    writable: true,
    configurable: true
  });
}

/**
 * Parse simple path.