Merge to XFA: Make the vast majority of JS headers private to src/javascript.

(cherry picked from commit 5b3d0208723f21c50b9922bdc500c9d78c359a25)
Original Review URL: https://codereview.chromium.org/1389783002 .

New changes to fix IWYU in:
  fpdfsdk/include/fpdfxfa/fpdfxfa_app.h
  xfa/include/fxfa/fxfa.h
  xfa/include/fxfa/fxfa_objectacc.h

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1388023003 .
diff --git a/fpdfsdk/src/javascript/JS_Object.cpp b/fpdfsdk/src/javascript/JS_Object.cpp
index 7898f48..0556c4e 100644
--- a/fpdfsdk/src/javascript/JS_Object.cpp
+++ b/fpdfsdk/src/javascript/JS_Object.cpp
@@ -4,10 +4,12 @@
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
+#include "JS_Object.h"
+
+#include "../../include/fsdk_mgr.h"  // For CPDFDoc_Environment.
 #include "../../include/javascript/IJavaScript.h"
-#include "../../include/javascript/JS_Context.h"
-#include "../../include/javascript/JS_Define.h"
-#include "../../include/javascript/JS_Object.h"
+#include "JS_Context.h"
+#include "JS_Define.h"
 
 namespace {