Set m_pLinearized to NULL after release

BUG=406868
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/504993002

core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index f1ca104..1b62b06 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -1509,6 +1509,7 @@
         CPDF_Object *pLen = m_pLinearized->GetDict()->GetElement(FX_BSTRC("L"));
         if (!pLen) {
             m_pLinearized->Release();
+            m_pLinearized = NULL;
             return FALSE;
         }
         if (pLen->GetInteger() != (int)pFileAccess->GetSize()) {