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_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index b64f82c..f4115f7 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -766,13 +766,13 @@
   static constexpr size_t kSpaceFilterOptimizingThreshold = 128;
   const CompilerOptions& compiler_options = compiler_driver->GetCompilerOptions();
   if ((compiler_options.GetCompilerFilter() == CompilerFilter::kSpace)
-      && (CodeItemInstructionAccessor(&dex_file, code_item).InsnsSizeInCodeUnits() >
+      && (CodeItemInstructionAccessor(dex_file, code_item).InsnsSizeInCodeUnits() >
           kSpaceFilterOptimizingThreshold)) {
     MaybeRecordStat(compilation_stats_.get(), MethodCompilationStat::kNotCompiledSpaceFilter);
     return nullptr;
   }
 
-  CodeItemDebugInfoAccessor code_item_accessor(&dex_file, code_item);
+  CodeItemDebugInfoAccessor code_item_accessor(dex_file, code_item);
   HGraph* graph = new (allocator) HGraph(
       allocator,
       arena_stack,