Fix an outstanding compaction bug in interpreter.

Fixed a bug in DoFieldPut where the FieldHelper GetType could cause
thread suspension which would result in a stale obj.

Added more handles in the class linker to facilitate moving fiels
and methods in the future.

Removed un-necessarly passing handle references since these are value
types and don't need to be passed by reference.

Added a special NullHandle type which allows null handles without a
handle scope.

Change-Id: I1b51723920a2e4f4f8b2907066f578a3e879fd5b
diff --git a/compiler/elf_writer_mclinker.cc b/compiler/elf_writer_mclinker.cc
index 0e27210..3dba426 100644
--- a/compiler/elf_writer_mclinker.cc
+++ b/compiler/elf_writer_mclinker.cc
@@ -361,10 +361,11 @@
       ClassLinker* linker = Runtime::Current()->GetClassLinker();
       // Unchecked as we hold mutator_lock_ on entry.
       ScopedObjectAccessUnchecked soa(Thread::Current());
-      StackHandleScope<2> hs(soa.Self());
+      StackHandleScope<1> hs(soa.Self());
       Handle<mirror::DexCache> dex_cache(hs.NewHandle(linker->FindDexCache(dex_file)));
-      auto class_loader(hs.NewHandle<mirror::ClassLoader>(nullptr));
-      method = linker->ResolveMethod(dex_file, method_idx, dex_cache, class_loader, NULL, invoke_type);
+      method = linker->ResolveMethod(dex_file, method_idx, dex_cache,
+                                     NullHandle<mirror::ClassLoader>(),
+                                     NullHandle<mirror::ArtMethod>(), invoke_type);
       CHECK(method != NULL);
     }
     const CompiledMethod* compiled_method =