[DevTools] enable async stacks by default

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

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 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:
  * 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 668 matching lines @@
     debugToolbar.appendToolbarItem(UI.Toolbar.createActionButton(this._stepOverAction));
     debugToolbar.appendToolbarItem(UI.Toolbar.createActionButton(this._stepIntoAction));
     debugToolbar.appendToolbarItem(UI.Toolbar.createActionButton(this._stepOutAction));
     debugToolbar.appendSeparator();
     debugToolbar.appendToolbarItem(UI.Toolbar.createActionButton(this._toggleBreakpointsActiveAction));
 
     this._pauseOnExceptionButton = new UI.ToolbarToggle('', 'largeicon-pause-on-exceptions');
     this._pauseOnExceptionButton.addEventListener(UI.ToolbarButton.Events.Click, this._togglePauseOnExceptions, this);
     debugToolbar.appendToolbarItem(this._pauseOnExceptionButton);
 
-    debugToolbar.appendSeparator();
-    debugToolbar.appendToolbarItem(new UI.ToolbarSettingCheckbox(
-        Common.moduleSetting('enableAsyncStackTraces'), Common.UIString('Capture async stack traces'),
-        Common.UIString('Async')));
-
     return debugToolbar;
   }
 
   _createDebugToolbarDrawer() {
     var debugToolbarDrawer = createElementWithClass('div', 'scripts-debug-toolbar-drawer');
 
     var label = Common.UIString('Pause On Caught Exceptions');
     var setting = Common.moduleSetting('pauseOnCaughtException');
     debugToolbarDrawer.appendChild(UI.SettingsUI.createSettingCheckbox(label, setting, true));
 
@@ skipping 596 matching lines @@
    */
   willHide() {
     UI.inspectorView.setDrawerMinimized(false);
     setImmediate(() => Sources.SourcesPanel.updateResizerAndSidebarButtons(Sources.SourcesPanel.instance()));
   }
 
   _showViewInWrapper() {
     this._view.show(this.element);
   }
 };