Repair flow graph printing after graph refactoring.

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_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 87 matching lines @@
   ASSERT(other_constant != NULL);
   return (value().raw() == other_constant->value().raw());
 }
 
 
 GraphEntryInstr::GraphEntryInstr(TargetEntryInstr* normal_entry)
     : BlockEntryInstr(CatchClauseNode::kInvalidTryIndex),
       normal_entry_(normal_entry),
       catch_entries_(),
       start_env_(NULL),
-      constant_null_(new ConstantInstr(Object::ZoneHandle())),
+      constant_null_(NULL),
       spill_slot_count_(0) {
 }
 
 
 MethodRecognizer::Kind MethodRecognizer::RecognizeKind(
     const Function& function) {
   // Only core and math library methods can be recognized.
   const Library& core_lib = Library::Handle(Library::CoreLibrary());
   const Library& core_impl_lib = Library::Handle(Library::CoreImplLibrary());
   const Library& math_lib = Library::Handle(Library::MathLibrary());
@@ skipping 1516 matching lines @@
     value->set_use_index(i);
     value->AddToEnvUseList();
   }
   instr->set_env(copy);
 }
 
 
 #undef __
 
 }  // namespace dart