Fix a bug in QuadTree.clear()

- According to this comment, only the root bounds should be resized: https://github.com/melonjs/melonJS/blob/61ed171238cbe75c842963e1fed7b66e7ab7f862/src/physics/quadtree.js#L281
- QuadTree nodes have a fake me.Rect for their bounds: https://github.com/melonjs/melonJS/blob/61ed171238cbe75c842963e1fed7b66e7ab7f862/src/physics/quadtree.js#L83-L88
- Together, these cause an exception when `bounds` is passed to the clear() method: "this.bounds.setShape is not a function"

Author: parasyte

src/physics/quadtree.js

@@ -271,7 +271,7 @@
         this.objects = [];
 
         for (var i = 0; i < this.nodes.length; i = i + 1) {
-            this.nodes[i].clear(bounds);
+            this.nodes[i].clear();
             // recycle the quadTree object
             QT_ARRAY_PUSH(this.nodes[i]);
         }