Add descriptions to transformation/transformers/es5/properties.mutators

src/babel/transformation/transformers/es5/properties.mutators.js

@@ -2,13 +2,40 @@ import * as defineMap from "../../helpers/define-map";
 import * as t from "../../../types";
 
 /**
- * [Please add a description.]
+ * Turn [object initializer mutators](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#Method_definitions)
+ * into `Object.defineProperties`.
+ *
+ * **In**
+ *
+ * ```javascript
+ * var foo = {
+ *   get bar() {
+ *     return "bar";
+ *   }
+ * };
+ * ```
+ *
+ * **Out**
+ *
+ * ```javascript
+ * var foo = Object.defineProperties({}, {
+ *   bar: {
+ *     get: function () {
+ *       return "bar";
+ *     },
+ *     enumerable: true,
+ *     configurable: true
+ *   }
+ * });
+ * ```
  */
 
 export var visitor = {
 
   /**
-   * [Please add a description.]
+   * Look for getters and setters on an object.
+   * Filter them out and wrap the object with an `Object.defineProperties` that
+   * defines the getters and setters.
    */
 
   ObjectExpression(node, parent, scope, file) {