bookmarks: unclip dnd separator.

chrome/browser/resources/bookmark_manager/css/bmm.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. */
 
 <include src="../search_header.css">
 
 html,
 body {
   cursor: default;
   height: 100%;
@@ skipping 242 matching lines @@
 #list,
 #tree-container {
   flex: 1;
 }
 
 #tree,
 #list {
   -webkit-padding-end: 5px;
   box-sizing: border-box;
   display: inline-block;
-  margin-bottom: 5px;
-  margin-top: 5px;
   min-width: 100%;
+  padding-bottom: 5px;
+  padding-top: 5px;
 }
 
 #tree {
   /* Only pad the tree as the splitter adds a lot of whitespace for the list. */
   -webkit-padding-start: 10px;
 }
 
 .tree-item > .tree-row {
   line-height: 20px;
 }
@@ skipping 96 matching lines @@
 
   list [editing] input,
   .tree-item [editing] input {
     padding: 3px 0;
   }
 
   .tree-row .expand-icon {
     top: 6px;
   }
 }