Add global opacity support to WebGL image replay

vectorLayer.setOpacity() now works as expected.

src/ol/renderer/webgl/webglvectorlayerrenderer.js

@@ -73,6 +73,7 @@ ol.renderer.webgl.VectorLayer.prototype.composeFrame =
     replayGroup.replay(context,
         viewState.center, viewState.resolution, viewState.rotation,
         frameState.size, frameState.extent, frameState.pixelRatio,
+        layerState.opacity,
         frameState.skippedFeatureUids);
   }