[Files] Prefer onclick property to listen click events.

This is a follow-up of CL:2354115.
As only one client listen to the click event of filter buttons, setting
onclick property is sufficient and concise over addEventListener.

Bug: none
Change-Id: I13b5ad9c658c8489ec50a99754db422a79dc5551
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359594Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798535}

ui/file_manager/file_manager/foreground/js/file_type_filters_controller.js

@@ -64,7 +64,7 @@ class FileTypeFiltersController {
   createFilterButton_(label) {
     const button = util.createChild(this.container_, 'file-type-filter-button');
     button.textContent = label;
-    button.addEventListener('click', this.onFilterButtonClicked_.bind(this));
+    button.onclick = this.onFilterButtonClicked_.bind(this);
     return button;
   }
 
@@ -87,7 +87,7 @@ class FileTypeFiltersController {
 
   /**
    * Updates the UI when one of the filter buttons is clicked.
-   * @param {!Event} event Event.
+   * @param {Event} event Event.
    * @private
    */
   onFilterButtonClicked_(event) {