Add canonicalize optimization for branches.

runtime/vm/intermediate_language.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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 1509 matching lines @@
   virtual LocationSummary* locs();
   virtual intptr_t DeoptimizationTarget() const;
   virtual Representation RequiredInputRepresentation(intptr_t i) const;
 
   // Replace the comparison with another, leaving the branch intact.
   void ReplaceWith(ComparisonInstr* other,
                    ForwardInstructionIterator* ignored) {
     comparison_ = other;
   }
 
+  virtual Instruction* Canonicalize(FlowGraphOptimizer* optimizer);
+
   virtual void PrintTo(BufferFormatter* f) const;
 
  private:
   ComparisonInstr* comparison_;
   const bool is_checked_;
 
   DISALLOW_COPY_AND_ASSIGN(BranchInstr);
 };
 
 
@@ skipping 2792 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_