Fix (nearly all) IWYU in fpdfskd/include/javascript/ headers.

fpdfsdk/include/jsapi/fxjs_v8.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
 
+// PDFium wrapper around V8 APIs. PDFium code should include this file rather
+// than including V8 headers directly.
+
 #ifndef FXJSAPI_H
 #define FXJSAPI_H
 
 #include <v8.h>
 #include "../../../core/include/fxcrt/fx_string.h"  // For CFX_WideString
 
+typedef v8::Value                       JSValue;
+typedef v8::Handle<v8::Object>  JSObject;
+typedef v8::Handle<v8::Object>  JSFXObject;
+
 enum FXJSOBJTYPE
 {
         JS_DYNAMIC = 0,
         JS_STATIC = 1,
 };
 
 enum FXJSVALUETYPE
 {
         VT_unknown,
         VT_string,
@@ skipping 99 matching lines @@
 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);
 
 #endif //FXJSAPI_H