Replace calls to deprecated CFX_{Wide,Byte}String::Empty()

xfa/fxfa/fm2js/xfa_fm2jsapi.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "xfa/fxfa/fm2js/xfa_fm2jsapi.h"
 
 #include "core/fxcrt/include/fx_basic.h"
 #include "xfa/fxfa/fm2js/xfa_fm2jscontext.h"
 #include "xfa/fxfa/fm2js/xfa_program.h"
 #include "xfa/fxfa/parser/xfa_document.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 int32_t XFA_FM2JS_Translate(const CFX_WideStringC& wsFormcalc,
                             CFX_WideTextBuf& wsJavascript,
                             CFX_WideString& wsError) {
   if (wsFormcalc.IsEmpty()) {
     wsJavascript.Clear();
-    wsError.Empty();
+    wsError.clear();
     return 0;
   }
   int32_t status = 0;
   CXFA_FMProgram program;
   status = program.Init(wsFormcalc);
   if (status) {
     wsError = program.GetError().message;
     return status;
   }
   status = program.ParseProgram();
@@ skipping 22 matching lines @@
   pContext->GlobalPropertyGetter(hValue);
 }
 void XFA_FM2JS_ContextRelease(XFA_HFM2JSCONTEXT hFM2JSContext) {
   CXFA_FM2JSContext* pContext =
       reinterpret_cast<CXFA_FM2JSContext*>(hFM2JSContext);
   pContext->Release();
 }
 #ifdef __cplusplus
 }
 #endif