DevTools: Preserve the selection in StylesSideBar more often

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

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * 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.
@@ skipping 1222 matching lines @@
     if (!this.editable)
       return;
 
     var targetElement = event.deepElementFromPoint();
     if (targetElement && !targetElement.isComponentSelectionCollapsed())
       return;
 
     if (!event.target.isComponentSelectionCollapsed())
       return;
 
+    if (this.propertiesTreeOutline.element.shadowRoot.firstChild &&
+        !this.propertiesTreeOutline.element.shadowRoot.firstChild.isComponentSelectionCollapsed())
+      return;
+
     if (this._checkWillCancelEditing())
       return;
 
     if (event.target.classList.contains('header') || this.element.classList.contains('read-only') ||
         event.target.enclosingNodeOrSelfWithClass('media')) {
       event.consume();
       return;
     }
     this.addNewBlankProperty().startEditing();
     event.consume(true);
@@ skipping 1823 matching lines @@
   }
 
   /**
    * @override
    * @return {!UI.ToolbarItem}
    */
   item() {
     return this._button;
   }
 };