Clean up CodeItemAccessors and Compact/StandardDexFile

Change constructor to use a reference to a dex file.

Remove duplicated logic for GetCodeItemSize.

Bug: 63756964
Test: test-art-host
Change-Id: I69af8b93abdf6bdfa4454e16db8f4e75883bca46
diff --git a/compiler/optimizing/optimizing_unit_test.h b/compiler/optimizing/optimizing_unit_test.h
index 661abb1..8c97d57 100644
--- a/compiler/optimizing/optimizing_unit_test.h
+++ b/compiler/optimizing/optimizing_unit_test.h
@@ -146,7 +146,7 @@
               /* access_flags */ 0u,
               /* verified_method */ nullptr,
               handles_->NewHandle<mirror::DexCache>(nullptr));
-      CodeItemDebugInfoAccessor accessor(&graph->GetDexFile(), code_item);
+      CodeItemDebugInfoAccessor accessor(graph->GetDexFile(), code_item);
       HGraphBuilder builder(graph, dex_compilation_unit, accessor, handles_.get(), return_type);
       bool graph_built = (builder.BuildGraph() == kAnalysisSuccess);
       return graph_built ? graph : nullptr;