Implement type cast in the VM.

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 89 matching lines @@
       return new LiteralNode(this->token_pos(), double_instance);
     }
   }
   return NULL;
 }
 
 
 bool ComparisonNode::IsKindValid() const {
   return Token::IsRelationalOperator(kind_)
       || Token::IsEqualityOperator(kind_)
-      || Token::IsInstanceofOperator(kind_);
+      || Token::IsTypeTestOperator(kind_)
+      || Token::IsTypeCastOperator(kind_);
 }
 
 
 const char* ComparisonNode::Name() const {
   return Token::Str(kind_);
 }
 
 
 const Instance* ComparisonNode::EvalConstExpr() const {
   const Instance* left_val = this->left()->EvalConstExpr();
@@ skipping 253 matching lines @@
     // 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;
 }
 
 }  // namespace dart