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

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

 /*
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 13 matching lines @@
  *
  */
 
 #include "core/layout/LayoutWordBreak.h"
 
 #include "core/html/HTMLElement.h"
 
 namespace blink {
 
 LayoutWordBreak::LayoutWordBreak(HTMLElement* element)
-    : LayoutText(element, StringImpl::empty()) {}
+    : LayoutText(element, StringImpl::empty) {}
 
 bool LayoutWordBreak::isWordBreak() const {
   return true;
 }
 
 }  // namespace blink