Sets the given framebuffer as the active and currently bound framebuffer.
If there was another framebuffer already bound it will force a pipeline flush.
Typically, you should call
pushFramebuffer instead of this method.
The framebuffer that needs to be bound.
If a framebuffer is given, set the gl scissor to match the frame buffer size? Or, if
Should the WebGL Textures be reset after the new framebuffer is bound?
Should the WebGL viewport be set?
This WebGLRenderer instance.