doc improvement:

1, provide type for callback argument
2, remove comment for $type to avoid jsdoc warning: "The @type tag does not permit a description;"

Author: jcyuan

src/structs/List.js

@@ -10,10 +10,9 @@ var NOOP = require('../utils/NOOP');
 var StableSort = require('../utils/array/StableSort');
 
 /**
- * @callback EachListCallback
- * @generic I - [item]
+ * @callback EachListCallback<I>
  *
- * @param {*} item - The item which is currently being processed.
+ * @param {I} item - The item which is currently being processed.
  * @param {...*} [args] - Additional arguments that will be passed to the callback, after the child.
  */
 
@@ -710,7 +709,7 @@ var List = new Class({
      *
      * @name Phaser.Structs.List#first
      * @genericUse {T} - [$type]
-     * @type {*} The first item in the List or `null` for an empty List.
+     * @type {*}
      * @readonly
      * @since 3.0.0
      */
@@ -737,7 +736,7 @@ var List = new Class({
      *
      * @name Phaser.Structs.List#last
      * @genericUse {T} - [$type]
-     * @type {*} The last item in the List, or `null` for an empty List.
+     * @type {*}
      * @readonly
      * @since 3.0.0
      */
@@ -766,7 +765,7 @@ var List = new Class({
      *
      * @name Phaser.Structs.List#next
      * @genericUse {T} - [$type]
-     * @type {*} The next item in the List, or `null` if the entire List has been traversed.
+     * @type {*}
      * @readonly
      * @since 3.0.0
      */
@@ -795,7 +794,7 @@ var List = new Class({
      *
      * @name Phaser.Structs.List#previous
      * @genericUse {T} - [$type]
-     * @type {*} The previous item in the List, or `null` if the entire List has been traversed.
+     * @type {*}
      * @readonly
      * @since 3.0.0
      */

src/structs/Map.js

@@ -7,11 +7,10 @@
 var Class = require('../utils/Class');
 
 /**
- * @callback EachMapCallback
- * @generic E - [entry]
+ * @callback EachMapCallback<E>
  *
  * @param {string} key - [description]
- * @param {*} entry - [description]
+ * @param {E} entry - [description]
  *
  * @return {?boolean} [description]
  */

src/structs/Set.js

@@ -7,10 +7,9 @@
 var Class = require('../utils/Class');
 
 /**
- * @callback EachSetCallback
- * @generic E - [entry]
+ * @callback EachSetCallback<E>
  *
- * @param {*} entry - [description]
+ * @param {E} entry - [description]
  * @param {number} index - [description]
  *
  * @return {?boolean} [description]