Split fpdfdoc/include/fpdf_doc.h into individual classes.

This CL splits the header file apart. The cpp files are not touched as part
of this CL, they will be done as a followup. This de-duplicates the fpdf_doc.h

BUG=pdfium:249

Review-Url: https://codereview.chromium.org/2183313004
diff --git a/fpdfsdk/javascript/PublicMethods.cpp b/fpdfsdk/javascript/PublicMethods.cpp
index fa7b5d4..34819c7 100644
--- a/fpdfsdk/javascript/PublicMethods.cpp
+++ b/fpdfsdk/javascript/PublicMethods.cpp
@@ -9,6 +9,7 @@
 #include <algorithm>
 #include <vector>
 
+#include "core/fpdfdoc/include/cpdf_interform.h"
 #include "core/fxcrt/include/fx_ext.h"
 #include "fpdfsdk/include/fsdk_mgr.h"
 #include "fpdfsdk/javascript/Field.h"