[DevTools] Remove Common.Event.target field.

third_party/WebKit/Source/devtools/front_end/sources/ThreadsSidebarPane.js

 // Copyright 2014 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.
 /**
  * @implements {SDK.TargetManager.Observer}
  * @unrestricted
  */
 Sources.ThreadsSidebarPane = class extends UI.VBox {
   constructor() {
     super();
@@ skipping 181 matching lines @@
     if (!target)
       return pendingTarget.name();
     var executionContext = target.runtimeModel.defaultExecutionContext();
     return executionContext && executionContext.label() ? executionContext.label() : target.name();
   }
 
   /**
    * @param {!Common.Event} event
    */
   _onDebuggerStateChanged(event) {
-    var debuggerModel = /** @type {!SDK.DebuggerModel} */ (event.target);
+    var debuggerModel = /** @type {!SDK.DebuggerModel} */ (event.data);
     var pendingTarget = this._targetToPending.get(debuggerModel.target());
     this._updateDebuggerState(pendingTarget);
   }
 
   /**
    * @param {!Common.Event} event
    */
   _onExecutionContextChanged(event) {
     var executionContext = /** @type {!SDK.ExecutionContext} */ (event.data);
     if (!executionContext.isDefault)
@@ skipping 130 matching lines @@
   }
 
   /**
    * @override
    * @return {string}
    */
   name() {
     return this._target.name();
   }
 };