Fix all relative includes to third_party.

testing/test_support.h

 // Copyright 2015 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TESTING_EMBEDDER_TEST_SUPPORT_H_
 #define TESTING_EMBEDDER_TEST_SUPPORT_H_
 
 #include <stdlib.h>
 #include <string>
 
 #include "../public/fpdfview.h"
 
 #ifdef PDF_ENABLE_V8
-#include "v8/include/libplatform/libplatform.h"
 #include "v8/include/v8.h"
-#endif
+#endif  // PDF_ENABLE_V8
 
 // Reads the entire contents of a file into a newly malloc'd buffer.
 char* GetFileContents(const char* filename, size_t* retlen);
 
 // Converts a FPDF_WIDESTRING to a std::wstring.
 // Deals with differences between UTF16LE and wchar_t.
 std::wstring GetWideString(FPDF_WIDESTRING wstr);
 
 #ifdef PDF_ENABLE_V8
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
@@ skipping 14 matching lines @@
                       unsigned long pos,
                       unsigned char* pBuf,
                       unsigned long size);
 
  private:
   const char* const m_pBuf;
   const size_t m_Len;
 };
 
 #endif  // TESTING_EMBEDDER_TEST_SUPPORT_H_