Examples: Clean up. (#27974)

examples/webgl_materials_wireframe.html

@@ -121,7 +121,6 @@
 						alphaToCoverage: true // only works when WebGLRenderer's "antialias" is set to "true"
 
 					} );
-					material2.extensions.derivatives = true;
 
 					mesh2 = new THREE.Mesh( geometry, material2 );
 					mesh2.position.set( 40, 0, 0 );