Create a typedef for HInstruction::GetInputs() return type.

And some other cleanup after
    https://android-review.googlesource.com/230742

Test: No new tests. ART test suite passed (tested on host).
Change-Id: I4743bf17544d0234c6ccb46dd0c1b9aae5c93e17
diff --git a/compiler/utils/transform_array_ref.h b/compiler/utils/transform_array_ref.h
index 6297b88..a6da34f 100644
--- a/compiler/utils/transform_array_ref.h
+++ b/compiler/utils/transform_array_ref.h
@@ -70,6 +70,11 @@
   TransformArrayRef(const ArrayRef<OtherBT>& base, Function fn)
       : data_(base, fn) { }
 
+  template <typename OtherBT,
+            typename = typename std::enable_if<std::is_same<BaseType, const OtherBT>::value>::type>
+  TransformArrayRef(const TransformArrayRef<OtherBT, Function>& other)
+      : TransformArrayRef(other.base(), other.GetFunction()) { }
+
   // Assignment operators.
 
   TransformArrayRef& operator=(const TransformArrayRef& other) = default;
@@ -149,6 +154,9 @@
   }
 
   Data data_;
+
+  template <typename OtherBT, typename OtherFunction>
+  friend class TransformArrayRef;
 };
 
 template <typename BaseType, typename Function>