The `BitmapMask.prevFramebuffer` property has been removed as it's no longer required, due to the fbo stack in the renderer.
The `BitmapMask.prevFramebuffer` property has been removed as it's no longer required, due to the fbo stack in the renderer.

photonstorm/phaser,photonstorm/phaser,BeanSeed/phaser,spayton/phaser,BeanSeed/phaser,spayton/phaser