Fix FieldGap priority queue ordering bug.

The priority queue for keeping track of gaps when packing fields in a
class object had the order reversed, giving priority to smaller gaps
instead of priority to larger gaps. This led to cases where fields
were not placed in gaps when they could be.

Bug: 22460222
Change-Id: I062e772e030c034adc227d75deed31c3322e203e
diff --git a/runtime/mirror/abstract_method.h b/runtime/mirror/abstract_method.h
index 99d697a..6240b3b 100644
--- a/runtime/mirror/abstract_method.h
+++ b/runtime/mirror/abstract_method.h
@@ -60,9 +60,8 @@
 
   HeapReference<mirror::Class> declaring_class_;
   HeapReference<mirror::Class> declaring_class_of_overridden_method_;
-  uint32_t padding_;
-  uint64_t art_method_;
   uint32_t access_flags_;
+  uint64_t art_method_;
   uint32_t dex_method_index_;
 
   friend struct art::AbstractMethodOffsets;  // for verifying offset information