Add type cast definitions for CPDF_Array.

core/src/fpdfdoc/doc_formcontrol.cpp

Index: core/src/fpdfdoc/doc_formcontrol.cpp
diff --git a/core/src/fpdfdoc/doc_formcontrol.cpp b/core/src/fpdfdoc/doc_formcontrol.cpp
index c5f47d20cb486160ea81d5e165c7c21ec34276ec..d29ac1e55b41ae52f78b6866b10f1953391d0d5e 100644
--- a/core/src/fpdfdoc/doc_formcontrol.cpp
+++ b/core/src/fpdfdoc/doc_formcontrol.cpp
@@ -86,14 +86,13 @@ CFX_ByteString CPDF_FormControl::GetCheckedAPState() {
   if (GetType() == CPDF_FormField::RadioButton ||
       GetType() == CPDF_FormField::CheckBox) {
     CPDF_Object* pOpt = FPDF_GetFieldAttr(m_pField->m_pDict, "Opt");
-    if (pOpt != NULL && pOpt->GetType() == PDFOBJ_ARRAY) {
+    if (pOpt && pOpt->IsArray()) {
       int iIndex = m_pField->GetControlIndex(this);
       csOn.Format("%d", iIndex);
     }
   }
-  if (csOn.IsEmpty()) {
+  if (csOn.IsEmpty())
     csOn = "Yes";
-  }
   return csOn;
 }
 CFX_WideString CPDF_FormControl::GetExportValue() {
@@ -103,9 +102,9 @@ CFX_WideString CPDF_FormControl::GetExportValue() {
   if (GetType() == CPDF_FormField::RadioButton ||
       GetType() == CPDF_FormField::CheckBox) {
     CPDF_Object* pOpt = FPDF_GetFieldAttr(m_pField->m_pDict, "Opt");
-    if (pOpt != NULL && pOpt->GetType() == PDFOBJ_ARRAY) {
+    if (CPDF_Array* pArray = ToArray(pOpt)) {
       int iIndex = m_pField->GetControlIndex(this);
-      csOn = ((CPDF_Array*)pOpt)->GetString(iIndex);
+      csOn = pArray->GetString(iIndex);
     }
   }
   if (csOn.IsEmpty()) {