Update call to sortFunction in copied / locally modified LayerControl.

_update function to use the options.sortFunction if present.  tbd:
if this should be offered via PR to upstream project.

Prettier formatting changes to pre-existing test file

src/mapml/control/LayerControl.js

@@ -98,10 +98,6 @@ export var LayerControl = L.Control.Layers.extend({
     }
   },
 
-  _withinZoomBounds: function (zoom, range) {
-    return range.min <= zoom && zoom <= range.max;
-  },
-
   // imported from leaflet with slight modifications
   // for layerControl ordering based on zIndex
   _update: function () {
@@ -122,9 +118,11 @@ export var LayerControl = L.Control.Layers.extend({
     // <----------- MODIFICATION from the default _update method
     // sort the layercontrol layers object based on the zIndex
     // provided by MapMLLayer
-    this._layers.sort(
-      (a, b) => a.layer.options.zIndex - b.layer.options.zIndex
-    );
+    if (this.options.sortLayers) {
+      this._layers.sort((a, b) =>
+        this.options.sortFunction(a.layer, b.layer, a.name, b.name)
+      );
+    }
     // -------------------------------------------------->
     for (i = 0; i < this._layers.length; i++) {
       obj = this._layers[i];

test/e2e/elements/map-extent/map-extent-checked-ordering.test.js

@@ -83,8 +83,8 @@ The imagery layer <map-extent> draws on top of the states layer.
       return +e._extentLayer._container.style.zIndex;
     });
     expect(statesZIndex).toEqual(1);
-    // TO DO re-order them via the DOM (insertAdjacentHTML), 
-    // ensure that 
+    // TO DO re-order them via the DOM (insertAdjacentHTML),
+    // ensure that
     // a) render order/z-index is correct
     // b) render order is reflected in layer control order as well
     // see https://github.com/Maps4HTML/Web-Map-Custom-Element/issues/956