Merge to XFA: Return error information from pdfium to JS.

Cherry-pick from b720d0a14601f1496ef15297bc46d401f5a2a890 +
Manually resolve merge conflicts +
Fix more IWYU to fix compile.

Original Review URL: https://codereview.chromium.org/963193003
TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/971013002
diff --git a/fpdfsdk/include/javascript/IJavaScript.h b/fpdfsdk/include/javascript/IJavaScript.h
index 91fd9c6..b0e21c9 100644
--- a/fpdfsdk/include/javascript/IJavaScript.h
+++ b/fpdfsdk/include/javascript/IJavaScript.h
@@ -7,6 +7,14 @@
 #ifndef _IJAVASCRIPT_H_
 #define _IJAVASCRIPT_H_
 
+#include "../../../core/include/fxcrt/fx_basic.h"
+#include "../../../xfa/include/fxjse/fxjse.h"
+
+class CPDF_Bookmark;
+class CPDF_FormField;
+class CPDFSDK_Annot;
+class CPDFSDK_Document;
+
 class IFXJS_Context
 {
 public: