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

third_party/WebKit/Source/wtf/text/StringImpl.h

Index: third_party/WebKit/Source/wtf/text/StringImpl.h
diff --git a/third_party/WebKit/Source/wtf/text/StringImpl.h b/third_party/WebKit/Source/wtf/text/StringImpl.h
index 77dfcc38d5f07621d4ee90d8cedea8e0c8425cc0..afdb6af132ebe2f62d4e824de43a744f48eccde6 100644
--- a/third_party/WebKit/Source/wtf/text/StringImpl.h
+++ b/third_party/WebKit/Source/wtf/text/StringImpl.h
@@ -205,8 +205,13 @@ class WTF_EXPORT StringImpl {
         m_isStatic(true) {}
 
  public:
+  static StringImpl* empty;
+  static StringImpl* empty16Bit;
+
   ~StringImpl();
 
+  static void initStatics();
+
   static StringImpl* createStatic(const char* string,
                                   unsigned length,
                                   unsigned hash);
@@ -324,9 +329,6 @@ class WTF_EXPORT StringImpl {
       destroyIfNotStatic();
   }
 
-  static StringImpl* empty();
-  static StringImpl* empty16Bit();
-
   // FIXME: Does this really belong in StringImpl?
   template <typename T>
   static void copyChars(T* destination,