Disable scroll on focus

CL:1593885 changed scrolling on focus behavior for the directory
tree.

A bug triggered by this change scrolls the entire client area
of the FilesApp under some focus changes.

This CL disables the scroll on focus completely.

Bug: 955566
Change-Id: I3b5d8b67501308ab5b5f3a69d3d373ec1127719b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1605382Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658394}

ui/file_manager/file_manager/foreground/js/ui/directory_tree.js

@@ -1791,9 +1791,6 @@ class DirectoryTree extends cr.ui.Tree {
         fileOperationManager, 'entries-changed',
         this.onEntriesChanged_.bind(this));
 
-    // Add a listener so we can scroll selected item into view.
-    this.addEventListener('focus', this.onFocus_.bind(this));
-
     this.addEventListener('click', (event) => {
       // Chromevox triggers |click| without switching focus, we force the focus
       // here so we can handle further keyboard/mouse events to expand/collapse