Implement IsNullCheck for CheckClassInstr. If input is nullable expected type, then check for null …

runtime/vm/il_printer.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/il_printer.h"
 
 #include "vm/intermediate_language.h"
 #include "vm/os.h"
 #include "vm/parser.h"
 
@@ skipping 775 matching lines @@
 
 void UnarySmiOpInstr::PrintOperandsTo(BufferFormatter* f) const {
   f->Print("%s, ", Token::Str(op_kind()));
   value()->PrintTo(f);
 }
 
 
 void CheckClassInstr::PrintOperandsTo(BufferFormatter* f) const {
   value()->PrintTo(f);
   PrintICData(f, unary_checks());
-  if (null_check()) {
+  if (IsNullCheck()) {
     f->Print(" nullcheck");
   }
 }
 
 
 void InvokeMathCFunctionInstr::PrintOperandsTo(BufferFormatter* f) const {
   f->Print("%s, ", MethodRecognizer::KindToCString(recognized_kind_));
   Definition::PrintOperandsTo(f);
 }
 
@@ skipping 163 matching lines @@
       f->Print(" [");
       locations_[i].PrintTo(f);
       f->Print("]");
     }
   }
   f->Print(" }");
   if (outer_ != NULL) outer_->PrintTo(f);
 }
 
 }  // namespace dart