Bad indexing in CPDF_Document::FindPageIndex when page tree corrupt.

core/fpdfapi/parser/cpdf_document.h

Index: core/fpdfapi/parser/cpdf_document.h
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index 65455480a47e1874a9afafc84f0fc44cab1b86d9..3848ad622090558ffc1577a2edeb758fcb7afa3f 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -106,9 +106,9 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
   // When this method is called, m_pTreeTraversal[level] exists.
   CPDF_Dictionary* TraversePDFPages(int iPage, int* nPagesToGo, size_t level);
   int FindPageIndex(CPDF_Dictionary* pNode,
-                    uint32_t& skip_count,
+                    uint32_t* skip_count,
                     uint32_t objnum,
-                    int& index,
+                    int* index,
                     int level = 0);
   std::unique_ptr<CPDF_Object> ParseIndirectObject(uint32_t objnum) override;
   void LoadDocInternal();