DevTools: Fix an exception on adding watch expression.

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

 /*
  * Copyright (C) IBM Corp. 2009  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 242 matching lines @@
   startEditing() {
     this._editing = true;
     this._element.removeChild(this._objectPresentationElement);
     var newDiv = this._element.createChild('div');
     newDiv.textContent = this._nameElement.textContent;
     this._textPrompt = new Components.ObjectPropertyPrompt();
     this._textPrompt.renderAsBlock();
     var proxyElement = this._textPrompt.attachAndStartEditing(newDiv, this._finishEditing.bind(this));
     proxyElement.classList.add('watch-expression-text-prompt-proxy');
     proxyElement.addEventListener('keydown', this._promptKeyDown.bind(this), false);
-    this._element.getComponentSelection().setBaseAndExtent(newDiv, 0, newDiv, 1);
+    this._element.getComponentSelection().selectAllChildren(newDiv);
   }
 
   /**
    * @return {boolean}
    */
   isEditing() {
     return !!this._editing;
   }
 
   /**
@@ skipping 143 matching lines @@
     InspectorFrontendHost.copyText(this._valueElement.textContent);
   }
 };
 
 Sources.WatchExpression._watchObjectGroupId = 'watch-group';
 
 /** @enum {symbol} */
 Sources.WatchExpression.Events = {
   ExpressionUpdated: Symbol('ExpressionUpdated')
 };