Clean up ImageHeader section getters.

Test: m art-test-host-gtest
Test: testrunner.py --host
Change-Id: Iaea7ce6f9bc3ff3c6d9bb6fb598aa62333ebf30c
diff --git a/dex2oat/dex2oat_test.cc b/dex2oat/dex2oat_test.cc
index db70e78..e10b171 100644
--- a/dex2oat/dex2oat_test.cc
+++ b/dex2oat/dex2oat_test.cc
@@ -840,7 +840,7 @@
       bool success = file->ReadFully(&image_header, sizeof(image_header));
       ASSERT_TRUE(success);
       ASSERT_TRUE(image_header.IsValid());
-      EXPECT_GT(image_header.GetImageSection(ImageHeader::kSectionObjects).Size(), 0u);
+      EXPECT_GT(image_header.GetObjectsSection().Size(), 0u);
     }
   }