Do not store cross ref v5 obj within document.

Currently, not necessary to store the cross ref v5 obj within
CPDF_IndirectObjectHolder(CPDF_Document), because all
necessary data from the cross ref are parsed or cloned, and
owned by CPDF_Parser seperately from CPDF_IndirectObjectHolder.

Also this fix regression from commit 4ea4459e.

BUG=chromium:810768

Change-Id: I0d1a11ff027210f4f15804a69d12416838ec9815
Reviewed-on: https://pdfium-review.googlesource.com/37110
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Art Snake <art-snake@yandex-team.ru>
diff --git a/core/fpdfapi/parser/cpdf_parser.cpp b/core/fpdfapi/parser/cpdf_parser.cpp
index e372f12..f7846ef 100644
--- a/core/fpdfapi/parser/cpdf_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_parser.cpp
@@ -977,16 +977,7 @@
   if (!objnum)
     return false;
 
-  CPDF_Object* pUnownedObject = pObject.get();
-  const CPDF_Dictionary* pRootDict = GetRoot();
-  if (pRootDict && pRootDict->GetObjNum() == objnum)
-    return false;
-  if (!m_pObjectsHolder->ReplaceIndirectObjectIfHigherGeneration(
-          objnum, std::move(pObject))) {
-    return false;
-  }
-
-  CPDF_Stream* pStream = pUnownedObject->AsStream();
+  CPDF_Stream* pStream = pObject->AsStream();
   if (!pStream)
     return false;