Revert "Revert "Cleanup some numeric code.""

fpdfsdk/src/javascript/PublicMethods.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 "PublicMethods.h"
 
 #include "../../include/fsdk_mgr.h"  // For CPDFDoc_Environment.
 #include "../../include/javascript/IJavaScript.h"
@@ skipping 98 matching lines @@
   }
 
   return TRUE;
 }
 
 FX_BOOL CJS_PublicMethods::IsDigit(wchar_t ch) {
   return (ch >= L'0' && ch <= L'9');
 }
 
 FX_BOOL CJS_PublicMethods::IsDigit(char ch) {
-  return (ch >= '0' && ch <= '9');
+  return std::isdigit(ch);
 }
 
 FX_BOOL CJS_PublicMethods::IsAlphabetic(wchar_t ch) {
   return ((ch >= L'a' && ch <= L'z') || (ch >= L'A' && ch <= L'Z'));
 }
 
 FX_BOOL CJS_PublicMethods::IsAlphaNumeric(wchar_t ch) {
   return (IsDigit(ch) || IsAlphabetic(ch));
 }
 
@@ skipping 1947 matching lines @@
     nums.SetElement(nIndex, CJS_Value(pRuntime, sPart.c_str()));
   }
 
   if (nums.GetLength() > 0)
     vRet = nums;
   else
     vRet.SetNull();
 
   return TRUE;
 }