Resize Renderer viewport on session end in WebXRManager

src/renderers/webvr/WebXRManager.js

@@ -93,6 +93,7 @@ function WebXRManager( renderer ) {
 	function onSessionEnd() {
 
 		renderer.setFramebuffer( null );
+		renderer.setRenderTarget( renderer.getRenderTarget() );
 		animation.stop();
 
 	}