Add test for CPDF_StreamParser::ReadHexString.

pdfium.gyp

 {
   'variables': {
     # TODO(thakis): Enable this, pdfium:29
     #'chromium_code': 1,
     'pdf_use_skia%': 0,
     'pdf_enable_v8%': 1,
     'conditions': [
       ['OS=="linux"', {
         'bundle_freetype%': 0,
       }, {  # On Android there's no system FreeType. On Windows and Mac, only a
@@ skipping 698 matching lines @@
         '<(DEPTH)/testing/gtest.gyp:gtest',
         'pdfium',
         'test_support',
       ],
       'include_dirs': [
         '<(DEPTH)'
       ],
       'sources': [
         'core/src/fpdfapi/fpdf_font/fpdf_font_cid_unittest.cpp',
         'core/src/fpdfapi/fpdf_font/fpdf_font_unittest.cpp',
+        'core/src/fpdfapi/fpdf_page/fpdf_page_parser_old_unittest.cpp',
         'core/src/fpdfapi/fpdf_parser/fpdf_parser_decode_unittest.cpp',
         'core/src/fxcodec/codec/fx_codec_jpx_unittest.cpp',
         'core/src/fxcrt/fx_basic_bstring_unittest.cpp',
         'core/src/fxcrt/fx_basic_memmgr_unittest.cpp',
         'core/src/fxcrt/fx_basic_wstring_unittest.cpp',
         'core/src/fxcrt/fx_bidi_unittest.cpp',
         'core/src/fxcrt/fx_system_unittest.cpp',
         'testing/fx_string_testhelpers.h',
         'testing/fx_string_testhelpers.cpp',
         'third_party/base/nonstd_unique_ptr_unittest.cpp',
@@ skipping 67 matching lines @@
           ],
           'dependencies': [
             '<(DEPTH)/v8/tools/gyp/v8.gyp:v8',
             '<(DEPTH)/v8/tools/gyp/v8.gyp:v8_libplatform',
           ],
         }],
       ],
     },
   ],
 }