code: function setupRenderBufferStorage( renderbuffer, renderTarget ) {
  
  		_gl.bindRenderbuffer( 36161, renderbuffer );
  
  		if ( renderTarget.depthBuffer && ! renderTarget.stencilBuffer ) {
  
  			_gl.renderbufferStorage( 36161, 33189, renderTarget.width, renderTarget.height );
  			_gl.framebufferRenderbuffer( 36160, 36096, 36161, renderbuffer );
  
  		} else if ( renderTarget.depthBuffer && renderTarget.stencilBuffer ) {
  
  			_gl.renderbufferStorage( 36161, 34041, renderTarget.width, renderTarget.height );
  			_gl.framebufferRenderbuffer( 36160, 33306, 36161, renderbuffer );
  
  		} else {
  
  			// FIXME: We don't support !depth !stencil
  			_gl.renderbufferStorage( 36161, 32854, renderTarget.width, renderTarget.height );
  
  		}
  
  		_gl.bindRenderbuffer( 36161, null );
  
  	}
docs: Setup storage for internal depth/stencil buffers and bind to correct framebuffer