Delete spurious js_type_check BUILD.gn target

Type checking should already be covered by the existing
js_type_check("closure_compile") BUILD.gn target.

Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ic3086629f3439237722f8f7b36a41031a7551901
Reviewed-on: https://chromium-review.googlesource.com/1100661Reviewed-by: calamity <calamity@chromium.org>
Reviewed-by: Sasha Morrissey <sashab@chromium.org>
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567514}

ui/file_manager/file_manager/background/js/BUILD.gn

@@ -34,12 +34,6 @@ js_type_check("closure_compile") {
   ]
 }
 
-js_type_check("media_import_handler_compile") {
-  deps = [
-    ":media_import_handler",
-  ]
-}
-
 js_library("app_window_wrapper") {
   deps = [
     ":app_windows",