extensions: fix dev controls spacing issue.

chrome/browser/resources/extensions/extensions.css

 /* Copyright (c) 2012 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. */
 
 html.loading * {
   transition-duration: 0 !important;
 }
 
 html:not(.focus-outline-visible)
 :enabled:focus:-webkit-any(input[type='checkbox'], input[type='radio']) {
@@ skipping 31 matching lines @@
 
 #dev-controls .button-container {
   display: flex;
   flex-wrap: wrap;
 }
 
 #dev-controls button {
   white-space: nowrap;
 }
 
+#dev-controls .button-container button:not(:last-of-type) {
+  -webkit-margin-end: 5px;
+}
+
 #apps-developer-tools-promo {
   align-items: center;
   border-top: 1px solid #eee;
   display: flex;
   font-size: 13px;
 }
 
 #apps-developer-tools-promo img {
   -webkit-margin-end: 5px;
   -webkit-margin-start: -5px;
@@ skipping 344 matching lines @@
 /* Sideload Wipeout */
 
 .sideload-wipeout-learn-more {
   text-decoration: none;
 }
 
 .sideload-wipeout-banner .page-banner-text {
   -webkit-padding-start: 8px;
   background-image: none;
 }