Replace more CFX_MapPtrToPtr and remove it.

BUILD.gn

 # 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.
 
 import("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_config") {
   cflags = []
@@ skipping 433 matching lines @@
     "core/include/fxcrt/fx_system.h",
     "core/include/fxcrt/fx_ucd.h",
     "core/include/fxcrt/fx_xml.h",
     "core/src/fxcrt/extension.h",
     "core/src/fxcrt/fx_basic_array.cpp",
     "core/src/fxcrt/fx_basic_bstring.cpp",
     "core/src/fxcrt/fx_basic_buffer.cpp",
     "core/src/fxcrt/fx_basic_coords.cpp",
     "core/src/fxcrt/fx_basic_gcc.cpp",
     "core/src/fxcrt/fx_basic_list.cpp",
-    "core/src/fxcrt/fx_basic_maps.cpp",
     "core/src/fxcrt/fx_basic_memmgr.cpp",
     "core/src/fxcrt/fx_basic_plex.cpp",
     "core/src/fxcrt/fx_basic_utf.cpp",
     "core/src/fxcrt/fx_basic_util.cpp",
     "core/src/fxcrt/fx_basic_wstring.cpp",
     "core/src/fxcrt/fx_bidi.cpp",
     "core/src/fxcrt/fx_extension.cpp",
     "core/src/fxcrt/fx_ucddata.cpp",
     "core/src/fxcrt/fx_unicode.cpp",
     "core/src/fxcrt/fx_xml_composer.cpp",
@@ skipping 318 matching lines @@
       "//v8:v8_libplatform",
     ]
     include_dirs += [
       "//v8",
       "//v8/include",
     ]
     configs += [ "//v8:external_startup_data" ]
   }
   configs += [ ":pdfium_config" ]
 }