Remove some c_str() calls from StringCs in xfa docs.

xfa/fxfa/app/xfa_fftextedit.cpp

Index: xfa/fxfa/app/xfa_fftextedit.cpp
diff --git a/xfa/fxfa/app/xfa_fftextedit.cpp b/xfa/fxfa/app/xfa_fftextedit.cpp
index f5605c9775f1d3e75eb35948f9c00f01094f8c5a..ea641f2066665b03f9d7eb1afb4d985099888f11 100644
--- a/xfa/fxfa/app/xfa_fftextedit.cpp
+++ b/xfa/fxfa/app/xfa_fftextedit.cpp
@@ -194,14 +194,13 @@ void CXFA_FFTextEdit::ValidateNumberField(const CFX_WideString& wsText) {
     if (pAppProvider) {
       CFX_WideString wsTitle;
       pAppProvider->LoadString(XFA_IDS_AppName, wsTitle);
-      CFX_WideString wsMessage;
       CFX_WideString wsError;
       pAppProvider->LoadString(XFA_IDS_ValidateNumberError, wsError);
       CFX_WideString wsSomField;
       pAcc->GetNode()->GetSOMExpression(wsSomField);
+      CFX_WideString wsMessage;
       wsMessage.Format(wsError.c_str(), wsText.c_str(), wsSomField.c_str());
-      pAppProvider->MsgBox(wsMessage.AsStringC(), wsTitle.AsStringC(),
-                           XFA_MBICON_Error, XFA_MB_OK);
+      pAppProvider->MsgBox(wsMessage, wsTitle, XFA_MBICON_Error, XFA_MB_OK);
     }
   }
 }