[WebUI] Fix rest of CSS style nits in misc. dirs so I can turn on CSS checker.

chrome/browser/resources/file_manager/css/common.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.
- */
+ * found in the LICENSE file. */
 
 /* This file contains "borrowed" copy of standard styles. To simplify merging,
  * when altering, please preserve original property value by adding comments.
  */
 input.common[type='checkbox'],
 input.common[type='radio'] {
   -webkit-appearance: none;
   -webkit-border-radius: 1px;
   -webkit-box-sizing: border-box;
-  border: 1px solid #C6C6C6;
+  border: 1px solid #c6c6c6;
   border-radius: 1px;
   box-sizing: border-box;
   cursor: default;
   height: 13px;
   margin: 0;
   width: 13px;
 }
 
 input.common[type='checkbox'] {
   position: relative;
 }
 
 input.common[type='checkbox']:checked::after {
   background-image: url('../images/common/check_no_box.png');
   background-position: -3px -4px;
 }
 
 input.common[type='checkbox']::after {
   content: '';
   display: -webkit-box;
   height: 15px;
   left: -2px;
   position: absolute;
   top: -2px;
   width: 17px;
 }