Use blocked scoped variables

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

src/ol/proj/transforms.js

@@ -8,7 +8,7 @@ import _ol_obj_ from '../obj.js';
  * @private
  * @type {Object.<string, Object.<string, ol.TransformFunction>>}
  */
-var transforms = {};
+let transforms = {};
 
 
 /**
@@ -28,8 +28,8 @@ export function clear() {
  * @param {ol.TransformFunction} transformFn Transform.
  */
 export function add(source, destination, transformFn) {
-  var sourceCode = source.getCode();
-  var destinationCode = destination.getCode();
+  const sourceCode = source.getCode();
+  const destinationCode = destination.getCode();
   if (!(sourceCode in transforms)) {
     transforms[sourceCode] = {};
   }
@@ -47,9 +47,9 @@ export function add(source, destination, transformFn) {
  * @return {ol.TransformFunction} transformFn The unregistered transform.
  */
 export function remove(source, destination) {
-  var sourceCode = source.getCode();
-  var destinationCode = destination.getCode();
-  var transform = transforms[sourceCode][destinationCode];
+  const sourceCode = source.getCode();
+  const destinationCode = destination.getCode();
+  const transform = transforms[sourceCode][destinationCode];
   delete transforms[sourceCode][destinationCode];
   if (_ol_obj_.isEmpty(transforms[sourceCode])) {
     delete transforms[sourceCode];
@@ -65,7 +65,7 @@ export function remove(source, destination) {
  * @return {ol.TransformFunction|undefined} The transform function (if found).
  */
 export function get(sourceCode, destinationCode) {
-  var transform;
+  let transform;
   if (sourceCode in transforms && destinationCode in transforms[sourceCode]) {
     transform = transforms[sourceCode][destinationCode];
   }