Repair flow graph printing after graph refactoring.

runtime/vm/flow_graph.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/flow_graph.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
@@ skipping 476 matching lines @@
 }
 
 
 void FlowGraph::Rename(GrowableArray<PhiInstr*>* live_phis) {
   // TODO(fschneider): Support catch-entry.
   if (graph_entry_->SuccessorCount() > 1) {
     Bailout("Catch-entry support in SSA.");
   }
 
   // Name global constants.
-  graph_entry_->constant_null()->set_ssa_temp_index(alloc_ssa_temp_index());
+  ConstantInstr* constant_null = new ConstantInstr(Object::ZoneHandle());
+  constant_null->set_ssa_temp_index(alloc_ssa_temp_index());
+  graph_entry_->set_constant_null(constant_null);
 
   // Initialize start environment.
   GrowableArray<Definition*> start_env(variable_count());
   for (intptr_t i = 0; i < parameter_count(); ++i) {
     ParameterInstr* param = new ParameterInstr(i, graph_entry_);
     param->set_ssa_temp_index(alloc_ssa_temp_index());  // New SSA temp.
     start_env.Add(param);
   }
 
   // All locals are initialized with #null.  Use the global definition, uses
@@ skipping 284 matching lines @@
   // Remove original arguments to the call.
   for (intptr_t i = 0; i < call->ArgumentCount(); ++i) {
     PushArgumentInstr* push = call->ArgumentAt(i);
     push->ReplaceUsesWith(push->value()->definition());
     push->RemoveFromGraph();
   }
 }
 
 
 }  // namespace dart