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/optimization.cc b/compiler/optimizing/optimization.cc
index 92b427c..57db7a6 100644
--- a/compiler/optimizing/optimization.cc
+++ b/compiler/optimizing/optimization.cc
@@ -242,7 +242,7 @@
         opt = new (allocator) HDeadCodeElimination(graph, stats, name);
         break;
       case OptimizationPass::kInliner: {
-        CodeItemDataAccessor accessor(dex_compilation_unit.GetDexFile(),
+        CodeItemDataAccessor accessor(*dex_compilation_unit.GetDexFile(),
                                       dex_compilation_unit.GetCodeItem());
         opt = new (allocator) HInliner(graph,                   // outer_graph
                                        graph,                   // outermost_graph