MD Downloads: remove most deprecated CSS imports

chrome/browser/resources/md_downloads/shared_style.css

Index: chrome/browser/resources/md_downloads/shared_style.css
diff --git a/chrome/browser/resources/md_downloads/shared_style.css b/chrome/browser/resources/md_downloads/shared_style.css
deleted file mode 100644
index 73d304a807f562092bf3e33f56a44854b9cb3c4e..0000000000000000000000000000000000000000
--- a/chrome/browser/resources/md_downloads/shared_style.css
+++ /dev/null
@@ -1,17 +0,0 @@
-/* Copyright 2015 The Chromium Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file. */
-
-* {
-  --downloads-item-width: 622px;
-}
-
-[hidden] {
-  display: none !important;
-}
-
-paper-button {
-  font-weight: 500;
-  margin: 0;
-  min-width: auto;
-}