Remove implicit conversions and some cleanup

core/src/fpdfdoc/doc_formfield.cpp

Index: core/src/fpdfdoc/doc_formfield.cpp
diff --git a/core/src/fpdfdoc/doc_formfield.cpp b/core/src/fpdfdoc/doc_formfield.cpp
index 7f85aff4d39a8b7bbdf8803d9edcc6d9b9da2bb3..a7cc484361ae45e8389d624bb0e3caffdbfe57bf 100644
--- a/core/src/fpdfdoc/doc_formfield.cpp
+++ b/core/src/fpdfdoc/doc_formfield.cpp
@@ -235,13 +235,12 @@ int CPDF_FormField::GetFieldType() {
   }
   return FIELDTYPE_UNKNOWN;
 }
+
 CPDF_AAction CPDF_FormField::GetAdditionalAction() {
   CPDF_Object* pObj = FPDF_GetFieldAttr(m_pDict, "AA");
-  if (!pObj) {
-    return NULL;
-  }
-  return pObj->GetDict();
+  return CPDF_AAction(pObj ? pObj->GetDict() : nullptr);
 }
+
 CFX_WideString CPDF_FormField::GetAlternateName() {
   CPDF_Object* pObj = FPDF_GetFieldAttr(m_pDict, "TU");
   if (!pObj) {