Fix behaviour of app.alert() with a single object argument.

fpdfsdk/src/javascript/JS_Value.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 FPDFSDK_SRC_JAVASCRIPT_JS_VALUE_H_
 #define FPDFSDK_SRC_JAVASCRIPT_JS_VALUE_H_
 
 #include "core/include/fxcrt/fx_basic.h"
@@ skipping 195 matching lines @@
 int JS_GetHourFromTime(double dt);
 int JS_GetMinFromTime(double dt);
 int JS_GetSecFromTime(double dt);
 double JS_DateParse(const wchar_t* string);
 double JS_MakeDay(int nYear, int nMonth, int nDay);
 double JS_MakeTime(int nHour, int nMin, int nSec, int nMs);
 double JS_MakeDate(double day, double time);
 bool JS_PortIsNan(double d);
 double JS_LocalTime(double d);
 
+// Some JS methods have the bizarre convention that they may also be called
+// with a single argument which is an object containing the actual arguments
+// as its properties. The varying arguments to this method are the property
+// names as wchar_t string literals corresponding to each positional argument.
+// The result will always contain |nKeywords| value, with unspecified ones
+// being set to type VT_unknown.
+std::vector<CJS_Value> JS_ExpandKeywordParams(
+    CJS_Runtime* pRuntime,
+    const std::vector<CJS_Value>& originals,
+    size_t nKeywords,
+    ...);
+
 #endif  // FPDFSDK_SRC_JAVASCRIPT_JS_VALUE_H_