DevTools: Fix an exception on adding watch expression.

third_party/WebKit/Source/devtools/front_end/elements/MetricsSidebarPane.js

 /*
  * Copyright (C) 2007 Apple 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 301 matching lines @@
     var boundKeyDown = this._handleKeyDown.bind(this, context, styleProperty);
     context.keyDownHandler = boundKeyDown;
     targetElement.addEventListener('keydown', boundKeyDown, false);
 
     this._isEditingMetrics = true;
 
     var config =
         new UI.InplaceEditor.Config(this._editingCommitted.bind(this), this.editingCancelled.bind(this), context);
     UI.InplaceEditor.startEditing(targetElement, config);
 
-    targetElement.getComponentSelection().setBaseAndExtent(targetElement, 0, targetElement, 1);
+    targetElement.getComponentSelection().selectAllChildren(targetElement);
   }
 
   _handleKeyDown(context, styleProperty, event) {
     var element = event.currentTarget;
 
     /**
      * @param {string} originalValue
      * @param {string} replacementString
      * @this {Elements.MetricsSidebarPane}
      */
@@ skipping 112 matching lines @@
       if (commitEditor)
         this.update();
     }
   }
 
   _editingCommitted(element, userInput, previousContent, context) {
     this.editingEnded(element, context);
     this._applyUserInput(element, userInput, previousContent, context, true);
   }
 };