Fix some issues with CXFA_FMParse/CXFA_FMLexer infinite looping.

xfa/src/fxfa/src/fm2js/xfa_fmparse.h

 // 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
 
 #ifndef _XFA_FM_PARSE_H
 #define _XFA_FM_PARSE_H
+
+#include <memory>
+
+#include "xfa/src/fxfa/src/fm2js/xfa_lexer.h"
+
 class CXFA_FMParse {
  public:
   CXFA_FMParse();
-  ~CXFA_FMParse();
   int32_t Init(const CFX_WideStringC& wsFormcalc, CXFA_FMErrorInfo* pErrorInfo);
   void NextToken();
   void Check(XFA_FM_TOKEN op);
   void Error(FX_DWORD lineNum, XFA_FM_ERRMSG msg, ...);
   CFX_PtrArray* ParseTopExpression();
   CXFA_FMExpression* ParseFunction();
   CXFA_FMExpression* ParseExpression();
   CXFA_FMExpression* ParseVarExpression();
   CXFA_FMExpression* ParseExpExpression();
   CXFA_FMExpression* ParseBlockExpression();
@@ skipping 10 matching lines @@
   CXFA_FMSimpleExpression* ParseEqualityExpression();
   CXFA_FMSimpleExpression* ParseRelationalExpression();
   CXFA_FMSimpleExpression* ParseAddtiveExpression();
   CXFA_FMSimpleExpression* ParseMultiplicativeExpression();
   CXFA_FMSimpleExpression* ParseUnaryExpression();
   CXFA_FMSimpleExpression* ParsePrimaryExpression();
   CXFA_FMSimpleExpression* ParsePostExpression(CXFA_FMSimpleExpression* e);
   CXFA_FMSimpleExpression* ParseIndexExpression();
 
  private:
-  const FX_WCHAR* m_pScript;
-  FX_STRSIZE m_uLength;
-  CXFA_FMLexer* m_lexer;
+  std::unique_ptr<CXFA_FMLexer> m_lexer;
   CXFA_FMToken* m_pToken;
   CXFA_FMErrorInfo* m_pErrorInfo;
 };
+
 #endif