Revert "Revert "Add basic image writer support for app images""

No changes, bug fixed in:
https://android-review.googlesource.com/#/c/180886/

Bug: 22858531

This reverts commit 4b018565e57c3349a3c1b5ec8ac9dae261c5e00b.

Change-Id: I86d9c2b55d535d803c6e1b3b8b4836bf6ff077e5
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 6053469..34b1bb2 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -871,8 +871,8 @@
       hs.NewHandle(dex_caches_object->AsObjectArray<mirror::DexCache>()));
 
   Handle<mirror::ObjectArray<mirror::Class>> class_roots(hs.NewHandle(
-          space->GetImageHeader().GetImageRoot(ImageHeader::kClassRoots)->
-          AsObjectArray<mirror::Class>()));
+      space->GetImageHeader().GetImageRoot(ImageHeader::kClassRoots)->
+      AsObjectArray<mirror::Class>()));
   class_roots_ = GcRoot<mirror::ObjectArray<mirror::Class>>(class_roots.Get());
 
   // Special case of setting up the String class early so that we can test arbitrary objects
@@ -881,7 +881,7 @@
 
   mirror::Class* java_lang_Object = GetClassRoot(kJavaLangObject);
   java_lang_Object->SetObjectSize(sizeof(mirror::Object));
-  Runtime::Current()->SetSentinel(Runtime::Current()->GetHeap()->AllocObject<true>(self,
+  Runtime::Current()->SetSentinel(heap->AllocObject<true>(self,
                                                           java_lang_Object,
                                                           java_lang_Object->GetObjectSize(),
                                                           VoidFunctor()));