Make CJS_PublicMethods::StrTrim() take a CFX_ByteString

Similar to https://codereview.chromium.org/1876203002 but in a
different file. The result is still not as efficient as possible
owing to the conversions back and forth to C types.

Convert these methods to ordinary functions in anon namespace
while we're at it.

Review URL: https://codereview.chromium.org/1882173002
diff --git a/fpdfsdk/javascript/PublicMethods.h b/fpdfsdk/javascript/PublicMethods.h
index 16cc5bc..67ca082 100644
--- a/fpdfsdk/javascript/PublicMethods.h
+++ b/fpdfsdk/javascript/PublicMethods.h
@@ -146,17 +146,9 @@
                                        const CFX_WideString& format);
   static double ParseNormalDate(const CFX_WideString& value,
                                 bool* bWrongFormat);
-  static double MakeInterDate(CFX_WideString strValue);
+  static double MakeInterDate(const CFX_WideString& value);
 
-  static CFX_WideString StrLTrim(const FX_WCHAR* pStr);
-  static CFX_WideString StrRTrim(const FX_WCHAR* pStr);
-  static CFX_WideString StrTrim(const FX_WCHAR* pStr);
-
-  static CFX_ByteString StrLTrim(const FX_CHAR* pStr);
-  static CFX_ByteString StrRTrim(const FX_CHAR* pStr);
-  static CFX_ByteString StrTrim(const FX_CHAR* pStr);
-
-  static bool IsNumber(const FX_WCHAR* string);
+  static bool IsNumber(const CFX_WideString& str);
 
   static bool maskSatisfied(wchar_t c_Change, wchar_t c_Mask);
   static bool isReservedMaskChar(wchar_t ch);