Examples: Fix MRT readback with WebGL backend. (#32505)

examples/webgpu_multiple_rendertargets_readback.html

@@ -155,27 +155,27 @@
 
 				torus.rotation.y = ( time / 1000 ) * .4;
 
-				const isMRT = selection === 'mrt';
+				const isReadback = ( selection !== 'mrt' );
 
 				// render scene into target
-				renderer.setMRT( isMRT ? sceneMRT : null );
-				renderer.setRenderTarget( isMRT ? renderTarget : readbackTarget );
+				renderer.setMRT( sceneMRT );
+				renderer.setRenderTarget( isReadback ? readbackTarget : renderTarget );
 				renderer.render( scene, camera );
 
 				// render post FX
 				renderer.setMRT( null );
 				renderer.setRenderTarget( null );
 
-				if ( isMRT ) {
-
-					quadMesh.material = material;
-
-				} else {
+				if ( isReadback ) {
 
 					quadMesh.material = readbackMaterial;
 
 					await readback();
 
+				} else {
+
+					quadMesh.material = material;
+
 				}
 
 				quadMesh.render( renderer );