[DevTools] Remove Common.Event.target field.

third_party/WebKit/Source/devtools/front_end/emulation/DeviceModeToolbar.js

 // Copyright 2016 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.
 /**
  * @unrestricted
  */
 Emulation.DeviceModeToolbar = class {
   /**
    * @param {!Emulation.DeviceModeModel} model
    * @param {!Common.Setting} showMediaInspectorSetting
@@ skipping 434 matching lines @@
   _modeMenuClicked(event) {
     var device = this._model.device();
     var model = this._model;
 
     if (device.modes.length === 2 && device.modes[0].orientation !== device.modes[1].orientation) {
       model.emulate(model.type(), model.device(), model.mode() === device.modes[0] ? device.modes[1] : device.modes[0]);
       return;
     }
 
     var contextMenu = new UI.ContextMenu(
-        /** @type {!Event} */ (event.data), false, event.target.element.totalOffsetLeft(),
-        event.target.element.totalOffsetTop() + event.target.element.offsetHeight);
+        /** @type {!Event} */ (event.data), false, this._modeButton.element.totalOffsetLeft(),
+        this._modeButton.element.totalOffsetTop() + this._modeButton.element.offsetHeight);
     addOrientation(Emulation.EmulatedDevice.Vertical, Common.UIString('Portrait'));
     addOrientation(Emulation.EmulatedDevice.Horizontal, Common.UIString('Landscape'));
     contextMenu.show();
 
     /**
      * @param {string} orientation
      * @param {string} title
      */
     function addOrientation(orientation, title) {
       var modes = device.modesForOrientation(orientation);
@@ skipping 114 matching lines @@
             this._emulateDevice(device);
             return;
           }
         }
       }
     }
 
     this._model.emulate(Emulation.DeviceModeModel.Type.Responsive, null, null);
   }
 };