DevTools: only allow status bar items in status bars.

Source/devtools/front_end/resources/resourcesPanel.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 55 matching lines @@
 }
 
 .resources.panel .base-storage-tree-element-title {
     overflow: hidden;
     position: relative;
     text-overflow: ellipsis;
     padding-left: 2px;
     top: 1px;
 }
 
-.resources-main {
-    position: absolute;
-    top: 0;
-    bottom: 23px;
-    left: 0;
-    right: 0;
-    display: flex;
-}
-
 .resources-status-bar {
-    position: absolute;
-    bottom: 0;
-    left: 0;
-    right: 0;
-    height: 23px;
+    border-top: 1px solid #ccc;
     background-color: #eee;
 }
 
 li.selected .base-storage-tree-element-subtitle {
     color: white;
 }
 
 .base-storage-tree-element-subtitle {
     padding-left: 2px;
     color: rgb(80, 80, 80);
@@ skipping 247 matching lines @@
     content: url(Images/cookie.png);
 }
 
 .application-cache-storage-tree-item .icon {
     content: url(Images/applicationCache.png);
 }
 
 .file-system-storage-tree-item .icon {
     content: url(Images/fileSystem.png);
 }