[DevTools] Expose left and right toolbar in TabbedPane.

third_party/WebKit/Source/devtools/front_end/ui/inspectorViewTabbedPane.css

 /*
  * 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.
  */
 
 .tabbed-pane-header-tab,
 .tabbed-pane-header-tab.selected {
     height: 26px;
     margin: 0;
     background: #f3f3f3;
     border: none;
     border-left: 2px solid transparent;
     border-right: 2px solid transparent;
     padding: 0 6px;
 }
 
 .tabbed-pane-header-tab.selected {
     border-width: 0 2px 0 2px;
 }
 
 .tabbed-pane-header-contents {
     margin-left: 0;
 }
+
+.tabbed-pane-left-toolbar {
+    margin-right: 0 !important;
+}