Get rid of most instance of 'foo != NULL'

core/src/fxcrt/fx_basic_utf.cpp

 // Copyright 2014 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.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/include/fxcrt/fx_basic.h"
 
 void CFX_UTF8Decoder::Clear() {
   m_Buffer.Clear();
@@ skipping 56 matching lines @@
     int code = unicode;
     m_Buffer.AppendChar(prefix[nbytes - 2] | (code / order));
     for (int i = 0; i < nbytes - 1; i++) {
       code = code % order;
       order >>= 6;
       m_Buffer.AppendChar(0x80 | (code / order));
     }
   }
 }
 CFX_ByteString FX_UTF8Encode(const FX_WCHAR* pwsStr, FX_STRSIZE len) {
-  FXSYS_assert(pwsStr != NULL);
+  FXSYS_assert(pwsStr);
   if (len < 0) {
     len = FXSYS_wcslen(pwsStr);
   }
   CFX_UTF8Encoder encoder;
   while (len-- > 0) {
     encoder.Input(*pwsStr++);
   }
   return encoder.GetResult();
 }