XFA unused function cleanup

xfa.gyp

 {
   "variables": {
     "pdf_enable_v8%": 1,
   },
   "target_defaults": {
     "defines": [
       "PDF_ENABLE_XFA",
     ],
     'msvs_disabled_warnings': [
       4005, 4018, 4146, 4333, 4345, 4267,
@@ skipping 635 matching lines @@
         "xfa/fxfa/parser/cxfa_validate.cpp",
         "xfa/fxfa/parser/cxfa_validate.h",
         "xfa/fxfa/parser/cxfa_value.cpp",
         "xfa/fxfa/parser/cxfa_value.h",
         "xfa/fxfa/parser/cxfa_widgetdata.cpp",
         "xfa/fxfa/parser/cxfa_widgetdata.h",
         "xfa/fxfa/parser/xfa_basic_data.cpp",
         "xfa/fxfa/parser/xfa_basic_data.h",
         "xfa/fxfa/parser/xfa_basic_imp.cpp",
         "xfa/fxfa/parser/xfa_basic_imp.h",
-        "xfa/fxfa/parser/xfa_docdata.h",
         "xfa/fxfa/parser/xfa_doclayout.h",
         "xfa/fxfa/parser/xfa_document.h",
         "xfa/fxfa/parser/xfa_document_datadescription_imp.cpp",
         "xfa/fxfa/parser/xfa_document_datadescription_imp.h",
         "xfa/fxfa/parser/xfa_document_datamerger_imp.cpp",
         "xfa/fxfa/parser/xfa_document_datamerger_imp.h",
         "xfa/fxfa/parser/xfa_document_imp.cpp",
         "xfa/fxfa/parser/xfa_document_layout_imp.cpp",
         "xfa/fxfa/parser/xfa_document_layout_imp.h",
         "xfa/fxfa/parser/xfa_document_serialize.cpp",
@@ skipping 103 matching lines @@
           "sources": [],
         }],
         ["OS == 'mac'", {
           "configurations": {},
           "sources": [],
         }],
       ]
     }
   ]
 }