Replace StringImpl::empty{16Bit}() with a static member

third_party/WebKit/Source/core/layout/LayoutCounter.cpp

 /**
  * Copyright (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 408 matching lines @@
       continue;
     if (stayWithin == parentElement(*currentLayoutObject) &&
         currentCounter->hasResetType())
       break;
     newNode->insertAfter(currentCounter, newNode->lastChild(), identifier);
   }
   return newNode.get();
 }
 
 LayoutCounter::LayoutCounter(Document* node, const CounterContent& counter)
-    : LayoutText(node, StringImpl::empty()),
+    : LayoutText(node, StringImpl::empty),
       m_counter(counter),
       m_counterNode(nullptr),
       m_nextForSameCounter(nullptr) {
   view()->addLayoutCounter();
 }
 
 LayoutCounter::~LayoutCounter() {}
 
 void LayoutCounter::willBeDestroyed() {
   if (m_counterNode) {
@@ skipping 265 matching lines @@
         current->parent(), current->previousSibling(), current->nextSibling(),
         current->hasCounterNodeMap()
             ? counterName ? blink::counterMaps().get(current)->get(identifier)
                           : (blink::CounterNode*)1
             : (blink::CounterNode*)0);
   }
   fflush(stderr);
 }
 
 #endif  // NDEBUG