GitLab

Adds
 - FileManagerJsTest.ImporterCommonTest
 - FileManagerJsTest.LRUCacheTest
 - FileManagerJsTest.AsyncUtilTest
 - FileManagerJsTest.FilesAppEntryTypes
 - FileManagerJsTest.UtilTest

Also adds test_importer_common.js to be typechecked, which isn't
itself a unit test. This exposed a weird dependency group on
ui/file_manager/exerns/volume_info.js - encapsulate those dependencies
as well as we can. Remove the dependency on cr.EventListenerType: it's
a @typedef {...|*} so adds no type safety and requires a dependency on
"//ui/webui/resources/js/cr:event_target" which is not an extern.

Bug: 860355
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: I479f8e7b22b56ea315c27fabc5e7ccdeb6277728
Reviewed-on: https://chromium-review.googlesource.com/c/1250762
Commit-Queue: Trent Apted <tapted@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597017}