DevTools: remove unused UI related code

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

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 369 matching lines @@
       this._softMenu.discard();
   }
 
   _innerShow() {
     if (typeof this._beforeShow === 'function') {
       this._beforeShow();
       delete this._beforeShow;
     }
 
     var menuObject = this._buildDescriptors();
-
-    UI._contextMenu = this;

[luoe, 2017/05/22 17:50:47]

Added:
https://chromium.googlesource.com/chromium/src/+/5189f94c96828d4422412f19411f...
Used to have a reference to the last shown ContextMenu so that
contextmenuitemselected calls from the Host
would route to the correct context menu.

Now, contextmenus listen for Host events themselves.

     if (this._useSoftMenu || UI.ContextMenu._useSoftMenu || InspectorFrontendHost.isHostedMode()) {
       this._softMenu = new UI.SoftContextMenu(menuObject, this._itemSelected.bind(this));
       this._softMenu.show(this._event.target.ownerDocument, new AnchorBox(this._x, this._y, 0, 0));
     } else {
       InspectorFrontendHost.showContextMenuAtPoint(this._x, this._y, menuObject, this._event.target.ownerDocument);
 
       /**
        * @this {UI.ContextMenu}
        */
       function listenToEvents() {
@@ skipping 75 matching lines @@
 UI.ContextMenu.Provider = function() {};
 
 UI.ContextMenu.Provider.prototype = {
   /**
    * @param {!Event} event
    * @param {!UI.ContextMenu} contextMenu
    * @param {!Object} target
    */
   appendApplicableItems(event, contextMenu, target) {}
 };