DevTools: Fix elements panel search in shadow host.

Source/core/inspector/InspectorDOMAgent.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google 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
@@ skipping 966 matching lines @@
 
     // Then traverse siblings of the node itself and its ancestors.
     const Node* node = &current;
     do {
         if (node == stayWithin)
             return 0;
         if (node->isShadowRoot()) {
             const ShadowRoot* shadowRoot = toShadowRoot(node);
             if (shadowRoot->olderShadowRoot())
                 return shadowRoot->olderShadowRoot();
+            Node* host = shadowRoot->host();
+            if (host && host->hasChildren())
+                return host->firstChild();
         }
         if (node->nextSibling())
             return node->nextSibling();
         node = node->isShadowRoot() ? toShadowRoot(node)->host() : node->parentNode();
     } while (node);
 
     return 0;
 }
 
 void InspectorDOMAgent::performSearch(ErrorString*, const String& whitespaceTrimmedQuery, const bool* optionalIncludeUserAgentShadowDOM, String* searchId, int* resultCount)
@@ skipping 1194 matching lines @@
     visitor->trace(m_searchResults);
 #endif
     visitor->trace(m_history);
     visitor->trace(m_domEditor);
     visitor->trace(m_listener);
     InspectorBaseAgent::trace(visitor);
 }
 
 } // namespace blink