DevTools: remove unused UI related code

third_party/WebKit/Source/devtools/front_end/ui/Panel.js

 /*
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  *
  * 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 88 matching lines @@
 
   /**
    * @param {!UI.Infobar} infobar
    */
   _onInfobarClosed(infobar) {
     infobar.element.remove();
     this.doResize();
   }
 };
 
-// Should by in sync with style declarations.
-UI.Panel.counterRightMargin = 25;

[luoe, 2017/05/22 17:50:48]

Added: 
https://chromium.googlesource.com/chromium/src/+/c0305576fdbe74e069ebc26bbdeb...
When Timeline had a records counter in the drawer, this margin was used in
Drawer.js to animate a slide to the right.

-
 /**
  * @unrestricted
  */
 UI.PanelWithSidebar = class extends UI.Panel {
   /**
    * @param {string} name
    * @param {number=} defaultWidth
    */
   constructor(name, defaultWidth) {
     super(name);
@@ skipping 26 matching lines @@
     return this._mainWidget.element;
   }
 
   /**
    * @return {!UI.SplitWidget}
    */
   splitWidget() {
     return this._panelSplitWidget;
   }
 };