Respect ToUnicode map when it maps a charcode to unicode 0

core/fpdftext/cpdf_textpage.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/fpdftext/include/cpdf_textpage.h"
 
 #include <algorithm>
 #include <utility>
@@ skipping 1113 matching lines @@
             CFX_FloatRect(charinfo.m_OriginX, charinfo.m_OriginY,
                           charinfo.m_OriginX, charinfo.m_OriginY);
         m_TempCharList.push_back(charinfo);
       }
       if (item.m_CharCode == CPDF_Font::kInvalidCharCode)
         continue;
     }
     spacing = 0;
     CFX_WideString wstrItem = pFont->UnicodeFromCharCode(item.m_CharCode);
     bool bNoUnicode = false;
-    FX_WCHAR wChar = wstrItem.GetAt(0);
-    if ((wstrItem.IsEmpty() || wChar == 0) && item.m_CharCode) {
-      if (wstrItem.IsEmpty())
-        wstrItem += (FX_WCHAR)item.m_CharCode;
-      else
-        wstrItem.SetAt(0, (FX_WCHAR)item.m_CharCode);
+    if (wstrItem.IsEmpty() && item.m_CharCode) {
+      wstrItem += static_cast<FX_WCHAR>(item.m_CharCode);
       bNoUnicode = true;
     }
     charinfo.m_Index = -1;
     charinfo.m_CharCode = item.m_CharCode;
     if (bNoUnicode)
       charinfo.m_Flag = FPDFTEXT_CHAR_UNUNICODE;
     else
       charinfo.m_Flag = FPDFTEXT_CHAR_NORMAL;
     charinfo.m_pTextObj = pTextObj;
     charinfo.m_OriginX = 0, charinfo.m_OriginY = 0;
@@ skipping 387 matching lines @@
                                  info.m_OriginY);
   return TRUE;
 }
 
 FX_BOOL CPDF_TextPage::IsRectIntersect(const CFX_FloatRect& rect1,
                                        const CFX_FloatRect& rect2) {
   CFX_FloatRect rect = rect1;
   rect.Intersect(rect2);
   return !rect.IsEmpty();
 }