Give a couple of char to int functions better names.

- FXSYS_toDecimalDigit() becomes FXSYS_DecimalCharToInt().
- FXSYS_toHexDigit() becomes FXSYS_HexCharToInt().

Change-Id: If4683e8f85f05124b92ff075056cbc295442087d
Reviewed-on: https://pdfium-review.googlesource.com/4930
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/javascript/PublicMethods.cpp b/fpdfsdk/javascript/PublicMethods.cpp
index 759fd91..2efcacd 100644
--- a/fpdfsdk/javascript/PublicMethods.cpp
+++ b/fpdfsdk/javascript/PublicMethods.cpp
@@ -238,7 +238,7 @@
     if (!std::iswdigit(c))
       break;
 
-    nRet = nRet * 10 + FXSYS_toDecimalDigit(c);
+    nRet = nRet * 10 + FXSYS_DecimalCharToInt(c);
     nSkip = i - nStart + 1;
     if (nSkip >= nMaxStep)
       break;