Fix ODR violation that can break WTF::String pretty printing in tests.

Source/wtf/testing/WTFTestPrintersTest.cpp

 /*
  * Copyright (C) 2013 Google 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:
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  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 11 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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  */
 
 #include "config.h"
-#include "wtf/testing/WTFTestHelpers.h"
 
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/CString.h"
 #include "wtf/text/WTFString.h"
 #include <gtest/gtest.h>
 #include <sstream>
 #include <string>
 
 using namespace WTF;
 
@@ skipping 19 matching lines @@
     EXPECT_EQ(CString("\"\\u007F\\u0080\\u0081\""), toCStringThroughPrinter("\x7F\x80\x81"));
     EXPECT_EQ(CString("\"\""), toCStringThroughPrinter(emptyString()));
     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))));
 
 }
 
 }