Change 'VM_NODES_INCREASE' to 100 or otherwise SpiderMonkey thinks 500 is too heavy for B2/C2. Address Dingping's review: 1) Change ._children to getChildren() and remove all ._position reference (._positionX/Y are created) 2) Remove all profiler-related code as they are not implemented 3) Finally, remove PerformanceVirtualMachineTest from JSB since this whole thing is really about cocos2d-html5 (but we still keep 1) 2) since it's a good practice to maintain JSB compatibility).