Fix layering violation in CPDF_Document::FromFPDFDocument().

fpdfsdk/src/fpdfformfill.cpp

Index: fpdfsdk/src/fpdfformfill.cpp
diff --git a/fpdfsdk/src/fpdfformfill.cpp b/fpdfsdk/src/fpdfformfill.cpp
index fed9a7e97e5429fd8c8c67ff9be800e850cfb155..02f906f5130754739118ce5dc8405e41221b4660 100644
--- a/fpdfsdk/src/fpdfformfill.cpp
+++ b/fpdfsdk/src/fpdfformfill.cpp
@@ -82,7 +82,7 @@ FPDFDOC_InitFormFillEnvironment(FPDF_DOCUMENT document,
   if (!formInfo || formInfo->version != 1)
     return nullptr;
 
-  CPDF_Document* pDocument = CPDF_Document::FromFPDFDocument(document);
+  CPDF_Document* pDocument = CPDFDocumentFromFPDFDocument(document);
   if (!pDocument)
     return nullptr;
   CPDFDoc_Environment* pEnv = new CPDFDoc_Environment(pDocument, formInfo);