Use blocked scoped variables

In addition to using const and let, this also upgrades our linter config and removes lint (mostly whitespace).

examples/getfeatureinfo-tile.js

@@ -4,23 +4,23 @@ import TileLayer from '../src/ol/layer/Tile.js';
 import TileWMS from '../src/ol/source/TileWMS.js';
 
 
-var wmsSource = new TileWMS({
+const wmsSource = new TileWMS({
   url: 'https://ahocevar.com/geoserver/wms',
   params: {'LAYERS': 'ne:ne', 'TILED': true},
   serverType: 'geoserver',
   crossOrigin: 'anonymous'
 });
 
-var wmsLayer = new TileLayer({
+const wmsLayer = new TileLayer({
   source: wmsSource
 });
 
-var view = new View({
+const view = new View({
   center: [0, 0],
   zoom: 1
 });
 
-var map = new Map({
+const map = new Map({
   layers: [wmsLayer],
   target: 'map',
   view: view
@@ -28,10 +28,10 @@ var map = new Map({
 
 map.on('singleclick', function(evt) {
   document.getElementById('info').innerHTML = '';
-  var viewResolution = /** @type {number} */ (view.getResolution());
-  var url = wmsSource.getGetFeatureInfoUrl(
-      evt.coordinate, viewResolution, 'EPSG:3857',
-      {'INFO_FORMAT': 'text/html'});
+  const viewResolution = /** @type {number} */ (view.getResolution());
+  const url = wmsSource.getGetFeatureInfoUrl(
+    evt.coordinate, viewResolution, 'EPSG:3857',
+    {'INFO_FORMAT': 'text/html'});
   if (url) {
     document.getElementById('info').innerHTML =
         '<iframe seamless src="' + url + '"></iframe>';
@@ -42,8 +42,8 @@ map.on('pointermove', function(evt) {
   if (evt.dragging) {
     return;
   }
-  var pixel = map.getEventPixel(evt.originalEvent);
-  var hit = map.forEachLayerAtPixel(pixel, function() {
+  const pixel = map.getEventPixel(evt.originalEvent);
+  const hit = map.forEachLayerAtPixel(pixel, function() {
     return true;
   });
   map.getTargetElement().style.cursor = hit ? 'pointer' : '';