Fix infinite recursion in CPDF_Parser::ParseIndirectObjectAt().

fpdfsdk/src/fpdfview_embeddertest.cpp

Index: fpdfsdk/src/fpdfview_embeddertest.cpp
diff --git a/fpdfsdk/src/fpdfview_embeddertest.cpp b/fpdfsdk/src/fpdfview_embeddertest.cpp
index ee32727aceac63978027f8897bf7611f9060ac3b..14a6532a5894c4e95de6c2c58af89464467a81ac 100644
--- a/fpdfsdk/src/fpdfview_embeddertest.cpp
+++ b/fpdfsdk/src/fpdfview_embeddertest.cpp
@@ -177,3 +177,8 @@ TEST_F(FPDFViewEmbeddertest, NamedDestsByName) {
   dest = FPDF_GetNamedDestByName(document(), "Bogus");
   EXPECT_EQ(nullptr, dest);
 }
+
+// The following tests pass if the document opens without crashing.
+TEST_F(FPDFViewEmbeddertest, Crashers) {
+  EXPECT_TRUE(OpenDocument("testing/resources/bug_451830.pdf"));
+}