Remove implicit cast from CFX_WideString to (const wchar_t*)

BUG=

Review URL: https://codereview.chromium.org/1882043004
diff --git a/fpdfsdk/javascript/PublicMethods.cpp b/fpdfsdk/javascript/PublicMethods.cpp
index d03f671..9f7b60f 100644
--- a/fpdfsdk/javascript/PublicMethods.cpp
+++ b/fpdfsdk/javascript/PublicMethods.cpp
@@ -1654,7 +1654,7 @@
   }
   CFX_WideString ws = params[0].ToCFXWideString();
   ws.Replace(L",", L".");
-  vRet = ws;
+  vRet = ws.c_str();
   vRet.MaybeCoerceToNumber();
   if (vRet.GetType() != CJS_Value::VT_number)
     vRet = 0;