Optimizing: Tag arena allocations in SsaBuilder.

Replace GrowableArray with ArenaVector in SsaBuilder and
tag allocations with a new arena allocation type.

Change-Id: I27312c51d7be9d2ad02a974cce93b365c65c5fc4
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 993cc37..70002ad 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -1544,7 +1544,7 @@
     }
   }
 
-  void CopyFrom(const GrowableArray<HInstruction*>& locals);
+  void CopyFrom(const ArenaVector<HInstruction*>& locals);
   void CopyFrom(HEnvironment* environment);
 
   // Copy from `env`. If it's a loop phi for `loop_header`, copy the first