Move-assign object in cpdf_object_walker_unittest.cpp

This skirts a spurious clang-analyzer warning.

Change-Id: Ibf3f3fff608a7d67f61085a6f6d410b94725755b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/100677
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fpdfapi/parser/cpdf_object_walker_unittest.cpp b/core/fpdfapi/parser/cpdf_object_walker_unittest.cpp
index 5e75c5f..ab0c2c3 100644
--- a/core/fpdfapi/parser/cpdf_object_walker_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_object_walker_unittest.cpp
@@ -94,7 +94,7 @@
   CPDF_ObjectWalker walker(level_0);
   while (RetainPtr<const CPDF_Object> obj = walker.GetNext()) {
     EXPECT_EQ(cur_parent, walker.GetParent());
-    cur_parent = obj;
+    cur_parent = std::move(obj);
   }
 }