Removed un-used vars.

Author: photonstorm

src/physics/p2/World.js

@@ -540,11 +540,6 @@ Phaser.Physics.P2.prototype = {
         if (typeof bottom === 'undefined') { bottom = true; }
         if (typeof setCollisionGroup === 'undefined') { setCollisionGroup = true; }
 
-        var hw = (width / 2);
-        var hh = (height / 2);
-        var cx = hw + x;
-        var cy = hh + y;
-
         if (this.walls.left)
         {
             this.world.removeBody(this.walls.left);