Avoid unneccary handle allocation in OptimizeTypeArguments.

runtime/vm/code_generator.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/code_generator.h"
 
 #include "vm/assembler_macros.h"
 #include "vm/ast.h"
 #include "vm/bigint_operations.h"
 #include "vm/code_patcher.h"
@@ skipping 397 matching lines @@
   if (!type_class.HasTypeArguments()) {
     return false;
   }
   AbstractTypeArguments& type_arguments =
       AbstractTypeArguments::Handle(instance.GetTypeArguments());
   if (type_arguments.IsNull()) {
     return false;
   }
   bool replaced = false;
   if (type_arguments.IsInstantiatedTypeArguments()) {
+    AbstractTypeArguments& uninstantiated = AbstractTypeArguments::Handle();
+    AbstractTypeArguments& instantiator = AbstractTypeArguments::Handle();
     do {
       const InstantiatedTypeArguments& instantiated_type_arguments =
           InstantiatedTypeArguments::Cast(type_arguments);
-      const AbstractTypeArguments& uninstantiated =
-          AbstractTypeArguments::Handle(
-              instantiated_type_arguments.uninstantiated_type_arguments());
-      const AbstractTypeArguments& instantiator =
-          AbstractTypeArguments::Handle(
-              instantiated_type_arguments.instantiator_type_arguments());
+      uninstantiated =
+          instantiated_type_arguments.uninstantiated_type_arguments();
+      instantiator = instantiated_type_arguments.instantiator_type_arguments();
       type_arguments = uninstantiated.InstantiateFrom(instantiator);
     } while (type_arguments.IsInstantiatedTypeArguments());
     AbstractTypeArguments& new_type_arguments = AbstractTypeArguments::Handle();
     new_type_arguments = type_arguments.Canonicalize();
     instance.SetTypeArguments(new_type_arguments);
     replaced = true;
   } else if (!type_arguments.IsCanonical()) {
     AbstractTypeArguments& new_type_arguments = AbstractTypeArguments::Handle();
     new_type_arguments = type_arguments.Canonicalize();
     instance.SetTypeArguments(new_type_arguments);
@@ skipping 1441 matching lines @@
   Isolate* isolate = Isolate::Current();
   StackZone zone(isolate);
   HANDLESCOPE(isolate);
   const Bigint& big_left = Bigint::Handle(left);
   const Bigint& big_right = Bigint::Handle(right);
   return BigintOperations::Compare(big_left, big_right);
 }
 END_LEAF_RUNTIME_ENTRY
 
 }  // namespace dart