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

third_party/WebKit/Source/wtf/text/WTFStringTest.cpp

 /*
  * Copyright (C) 2012 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 427 matching lines @@
   string8.ensure16Bit();
   EXPECT_FALSE(string8.is8Bit());
   EXPECT_EQ("8bit", string8);
 
   String string16(reinterpret_cast<const UChar*>(u"16bit"));
   EXPECT_FALSE(string16.is8Bit());
   string16.ensure16Bit();
   EXPECT_FALSE(string16.is8Bit());
   EXPECT_EQ("16bit", string16);
 
-  String empty8(StringImpl::empty());
+  String empty8(StringImpl::empty);
   EXPECT_TRUE(empty8.is8Bit());
   empty8.ensure16Bit();
   EXPECT_FALSE(empty8.is8Bit());
   EXPECT_TRUE(empty8.isEmpty());
   EXPECT_FALSE(empty8.isNull());
 
-  String empty16(StringImpl::empty16Bit());
+  String empty16(StringImpl::empty16Bit);
   EXPECT_FALSE(empty16.is8Bit());
   empty16.ensure16Bit();
   EXPECT_FALSE(empty16.is8Bit());
   EXPECT_TRUE(empty16.isEmpty());
   EXPECT_FALSE(empty16.isNull());
 
   String nullString;
   nullString.ensure16Bit();
   EXPECT_TRUE(nullString.isNull());
 }
@@ skipping 27 matching lines @@
   EXPECT_EQ(CString("<null>"), toCStringThroughPrinter(String()));
 
   static const UChar unicodeSample[] = {0x30C6, 0x30B9,
                                         0x30C8};  // "Test" in Japanese.
   EXPECT_EQ(CString("\"\\u30C6\\u30B9\\u30C8\""),
             toCStringThroughPrinter(
                 String(unicodeSample, WTF_ARRAY_LENGTH(unicodeSample))));
 }
 
 }  // namespace WTF