Add type cast definitions for CPDF_Array.

core/include/fpdfapi/fpdf_objects.h

Index: core/include/fpdfapi/fpdf_objects.h
diff --git a/core/include/fpdfapi/fpdf_objects.h b/core/include/fpdfapi/fpdf_objects.h
index 2404774dcbf6f5f4c7813388193dd0629273c449..162a514cd7dae3c42c28a8bc90b9aabd7af9e617 100644
--- a/core/include/fpdfapi/fpdf_objects.h
+++ b/core/include/fpdfapi/fpdf_objects.h
@@ -79,12 +79,16 @@ class CPDF_Object {
 
   FX_BOOL IsModified() const { return FALSE; }
 
+  bool IsArray() const { return m_Type == PDFOBJ_ARRAY; }
   bool IsBoolean() const { return m_Type == PDFOBJ_BOOLEAN; }
   bool IsDictionary() const { return m_Type == PDFOBJ_DICTIONARY; }
   bool IsName() const { return m_Type == PDFOBJ_NAME; }
   bool IsNumber() const { return m_Type == PDFOBJ_NUMBER; }
   bool IsString() const { return m_Type == PDFOBJ_STRING; }
 
+  CPDF_Array* AsArray();
+  const CPDF_Array* AsArray() const;
+
   CPDF_Boolean* AsBoolean();
   const CPDF_Boolean* AsBoolean() const;
 
@@ -341,6 +345,13 @@ class CPDF_Array : public CPDF_Object {
   CFX_PtrArray m_Objects;
   friend class CPDF_Object;
 };
+inline CPDF_Array* ToArray(CPDF_Object* obj) {
+  return obj ? obj->AsArray() : nullptr;
+}
+inline const CPDF_Array* ToArray(const CPDF_Object* obj) {
+  return obj ? obj->AsArray() : nullptr;
+}
+
 class CPDF_Dictionary : public CPDF_Object {
  public:
   static CPDF_Dictionary* Create() { return new CPDF_Dictionary(); }