Revert "Revert "Revert "Cleanup some numeric code."""

core/src/fxcrt/fx_basic_bstring.cpp

Index: core/src/fxcrt/fx_basic_bstring.cpp
diff --git a/core/src/fxcrt/fx_basic_bstring.cpp b/core/src/fxcrt/fx_basic_bstring.cpp
index 1b9d7a03444dc08b908dff1ac4cc20bea74b3924..c706912d9da87c2bc226dcb89c30b185f90a2abd 100644
--- a/core/src/fxcrt/fx_basic_bstring.cpp
+++ b/core/src/fxcrt/fx_basic_bstring.cpp
@@ -5,7 +5,6 @@
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include <stddef.h>  // For offsetof().
-#include <cctype>
 
 #include "../../include/fxcrt/fx_basic.h"
 #include "../../../third_party/base/numerics/safe_math.h"
@@ -494,8 +493,8 @@ void CFX_ByteString::FormatV(const FX_CHAR* lpszFormat, va_list argList) {
     }
     if (nWidth == 0) {
       nWidth = FXSYS_atoi(lpsz);
-      while (std::isdigit(*lpsz))
-        lpsz++;
+      for (; (*lpsz) >= '0' && (*lpsz) <= '9'; lpsz++)
+        ;
     }
     if (nWidth < 0 || nWidth > 128 * 1024) {
       lpszFormat = "Bad width";
@@ -510,8 +509,8 @@ void CFX_ByteString::FormatV(const FX_CHAR* lpszFormat, va_list argList) {
         lpsz++;
       } else {
         nPrecision = FXSYS_atoi(lpsz);
-        while (std::isdigit(*lpsz))
-          lpsz++;
+        for (; (*lpsz) >= '0' && (*lpsz) <= '9'; lpsz++)
+          ;
       }
     }
     if (nPrecision < 0 || nPrecision > 128 * 1024) {