[lazyProperty] Lazy getters on JS classes.

lazyProperty.js

**
 * Lazily-evaluated getters.
 *
 * ```js
 * class Person {
 *   get name() {
 *     lazyProperty(this, 'name', calculateSomeValueForName())
 *     return this.name
 *   }
 * }
 * ```
 *
 * @param {any} context - `this` from the class.
 * @param {string} propertyName - The name of the property on the class.
 * @param {any} value - The value to cache.
 */
export function lazyProperty(context, propertyName, value) {
  Object.defineProperty(context, propertyName, {
    value,
    writable: false,
    configurable: true,
  });
}