Remove layerState param from prepareFrame and renderFrame function

rendering/cases/layer-group/main.js

@@ -0,0 +1,30 @@
+import Map from '../../../src/ol/Map.js';
+import View from '../../../src/ol/View.js';
+import {Group as LayerGroup, Tile as TileLayer} from '../../../src/ol/layer.js';
+import XYZ from '../../../src/ol/source/XYZ';
+
+new Map({
+  target: 'map',
+  view: new View({
+    center: [0, 0],
+    zoom: 3
+  }),
+  layers: new LayerGroup({
+    opacity: 0.75,
+    layers: [
+      new TileLayer({
+        opacity: 0.25,
+        source: new XYZ({
+          url: '/data/tiles/satellite/{z}/{x}/{y}.jpg'
+        })
+      }),
+      new TileLayer({
+        source: new XYZ({
+          url: '/data/tiles/stamen-labels/{z}/{x}/{y}.png'
+        })
+      })
+    ]
+  })
+});
+
+render();