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

Source/platform/network/HTTPParsersTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "HTTPParsers.h"
 
 #include "wtf/MathExtras.h"
-#include "wtf/testing/WTFTestHelpers.h"
 #include "wtf/text/AtomicString.h"
 
 #include <gtest/gtest.h>
 
 namespace blink {
 
 namespace {
 
 size_t parseHTTPHeader(const char* data, String& failureReason, AtomicString& nameStr, AtomicString& valueStr)
 {
@@ skipping 215 matching lines @@
     EXPECT_FALSE(set2.contains("dpr"));
     EXPECT_FALSE(set2.contains("rw"));
     EXPECT_FALSE(set2.contains("whatever"));
     EXPECT_TRUE(set2.contains("dprw"));
     EXPECT_FALSE(set2.contains("foo"));
     EXPECT_TRUE(set2.contains("fo\to"));
 }
 
 } // namespace blink