Remove pesky JS presubmit nits for the runtime loaded test utils

Bug: None
Change-Id: Ief982eb1150918c8f995f6b26332bc594924b856
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1950374Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721905}

ui/file_manager/file_manager/background/js/runtime_loaded_test_util.js

@@ -75,14 +75,14 @@ function extractElementInfo(element, contentWindow, opt_styleNames) {
  */
 test.util.sync.getWindows = () => {
   const windows = {};
-  for (var id in window.appWindows) {
+  for (const id in window.appWindows) {
     const windowWrapper = window.appWindows[id];
     windows[id] = {
       outerWidth: windowWrapper.contentWindow.outerWidth,
       outerHeight: windowWrapper.contentWindow.outerHeight
     };
   }
-  for (var id in window.background.dialogs) {
+  for (const id in window.background.dialogs) {
     windows[id] = {
       outerWidth: window.background.dialogs[id].outerWidth,
       outerHeight: window.background.dialogs[id].outerHeight
@@ -341,8 +341,8 @@ test.util.sync.setScrollTop = (contentWindow, query, position) => {
  */
 test.util.sync.setElementStyles = (contentWindow, query, properties) => {
   const element = contentWindow.document.querySelector(query);
-  for (let [prop, value] of Object.entries(properties)) {
-    element.style[prop] = value;
+  for (const [key, value] of Object.entries(properties)) {
+    element.style[key] = value;
   }
 };
 
@@ -370,10 +370,10 @@ test.util.sync.sendEvent = (contentWindow, targetQuery, event) => {
   } else if (typeof targetQuery === 'string') {
     target = contentWindow.document.querySelector(targetQuery);
   } else if (Array.isArray(targetQuery)) {
-    let elems = test.util.sync.deepQuerySelectorAll_(
+    const elements = test.util.sync.deepQuerySelectorAll_(
         contentWindow.document, targetQuery);
-    if (elems.length > 0) {
-      target = elems[0];
+    if (elements.length > 0) {
+      target = elements[0];
     }
   }