fix argument name in comment on Phaser.Physics.Arcade#getObjectsAtLocation.

Author: micahrj

src/physics/arcade/World.js

@@ -1434,7 +1434,7 @@ Phaser.Physics.Arcade.prototype = {
     * Note that the children are not checked for depth order, but simply if they overlap the coordinate or not.
     *
     * @method Phaser.Physics.Arcade#getObjectsAtLocation
-    * @param {number} pointer - The x coordinate to check.
+    * @param {number} x - The x coordinate to check.
     * @param {number} y - The y coordinate to check.
     * @param {Phaser.Group} group - The Group to check.
     * @param {function} [callback] - A callback function that is called if the object overlaps the coordinates. The callback will be sent two parameters: the callbackArg and the Object that overlapped the location.