Compile fuzzer sources in standalone builds. (try 2)

testing/libfuzzer/pdf_fm2js_fuzzer.cc

 // Copyright 2016 The 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.
 
 #include <cstddef>
 #include <cstdint>
 
 #include "core/fxcrt/fx_basic.h"
+#include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_string.h"
 #include "xfa/fxfa/fm2js/xfa_program.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  if (size > std::numeric_limits<FX_STRSIZE>::max())
+  FX_SAFE_STRSIZE safe_size = size;
+  if (!safe_size.IsValid())
     return 0;
 
-  CFX_WideString input = CFX_WideString::FromUTF8(
-      CFX_ByteStringC(data, static_cast<FX_STRSIZE>(size)));
+  CFX_WideString input =
+      CFX_WideString::FromUTF8(CFX_ByteStringC(data, safe_size.ValueOrDie()));
   CXFA_FMProgram program;
   if (program.Init(input.AsStringC()) || program.ParseProgram())
     return 0;
 
   CFX_WideTextBuf js;
   program.TranslateProgram(js);
   return 0;
 }