Use VM type cast and save handles.

runtime/vm/ast.cc

 // Copyright (c) 2011, 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/ast.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/isolate.h"
 #include "vm/object_store.h"
 
@@ skipping 65 matching lines @@
   for (intptr_t i = 0; i < this->length(); i++) {
     ElementAt(i)->Visit(visitor);
   }
 }
 
 
 // TODO(srdjan): Add code for logical negation.
 AstNode* LiteralNode::ApplyUnaryOp(Token::Kind unary_op_kind) {
   if (unary_op_kind == Token::kSUB) {
     if (literal().IsSmi()) {
-      Smi& smi = Smi::Handle();
-      smi ^= literal().raw();
+      const Smi& smi = Smi::Cast(literal());
       const Instance& literal =
           Instance::ZoneHandle(Integer::New(-smi.Value()));
       return new LiteralNode(this->token_pos(), literal);
     }
     if (literal().IsDouble()) {
-      Double& dbl = Double::Handle();
-      dbl ^= literal().raw();
+      const Double& dbl = Double::Cast(literal());
       // Preserve negative zero.
       double new_value = (dbl.value() == 0.0) ? -0.0 : (0.0 - dbl.value());
       Double& double_instance =
           Double::ZoneHandle(Double::New(new_value, Heap::kOld));
       double_instance ^= double_instance.Canonicalize();
       return new LiteralNode(this->token_pos(), double_instance);
     }
   }
   return NULL;
 }
@@ skipping 264 matching lines @@
   const Object& result =
       Object::Handle(DartEntry::InvokeStatic(getter_func,
                                              arguments,
                                              kNoArgumentNames));
   if (result.IsError() || result.IsNull()) {
     // TODO(turnidge): We could get better error messages by returning
     // the Error object directly to the parser.  This will involve
     // replumbing all of the EvalConstExpr methods.
     return NULL;
   }
-  Instance& field_value = Instance::ZoneHandle();
-  field_value ^= result.raw();
-  return &field_value;
+  return &Instance::ZoneHandle(Instance::Cast(result).raw());
 }
 
 }  // namespace dart