Fix potential NRE in CCNode Pause and Resume.  This is happening intermittently when using CCLayerMultiplex.
Fix potential NRE in CCNode Pause and Resume.  This is happening intermittently when using CCLayerMultiplex.

zmaruo/CocosSharp,haithemaraissia/CocosSharp,TukekeSoft/CocosSharp,TukekeSoft/CocosSharp,MSylvia/CocosSharp,zmaruo/CocosSharp,mono/CocosSharp,MSylvia/CocosSharp,haithemaraissia/CocosSharp,mono/CocosSharp