Use VM type cast and save handles.

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 571 matching lines @@
   if (index == 0) return true_successor_;
   if (index == 1) return false_successor_;
   UNREACHABLE();
   return NULL;
 }
 
 
 // ==== Support for propagating static type.
 RawAbstractType* ConstantVal::StaticType() const {
   if (value().IsInstance()) {
-    Instance& instance = Instance::Handle();
-    instance ^= value().raw();
-    return instance.GetType();
+    return Instance::Cast(value()).GetType();
   } else {
     UNREACHABLE();
     return AbstractType::null();
   }
 }
 
 
 RawAbstractType* UseVal::StaticType() const {
   return definition()->StaticType();
 }
@@ skipping 733 matching lines @@
   const ExternalLabel label(closure_function.ToCString(), stub.EntryPoint());
   compiler->GenerateCall(token_pos(), try_index(), &label,
                          PcDescriptors::kOther);
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 
 #undef __
 
 }  // namespace dart