Fix branch optimizations based on range analysis.

runtime/vm/flow_graph_optimizer.h

 // 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.
 
 #ifndef VM_FLOW_GRAPH_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph.h"
 
@@ skipping 313 matching lines @@
   // }
   //
   // where b is known to be null.
   static void OptimizeBranches(FlowGraph* graph);
 
   // Used to initialize the abstract value of definitions.
   static RawObject* Unknown() { return Object::unknown_constant().raw(); }
 
  private:
   void Analyze();
-  void VisitBranches();
   void Transform();
   void EliminateRedundantBranches();
 
   void SetReachable(BlockEntryInstr* block);
   void SetValue(Definition* definition, const Object& value);
 
   // Assign the join (least upper bound) of a pair of abstract values to the
   // first one.
   void Join(Object* left, const Object& right);
 
@@ skipping 107 matching lines @@
 // Optimize spill stores inside try-blocks by identifying values that always
 // contain a single known constant at catch block entry.
 class TryCatchAnalyzer : public AllStatic {
  public:
   static void Optimize(FlowGraph* flow_graph);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_