Refactor AOT deduplication steps so they can run before an app-jit snapshot as well.

runtime/vm/program_visitor.h

 // Copyright (c) 2015, 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 RUNTIME_VM_PROGRAM_VISITOR_H_
 #define RUNTIME_VM_PROGRAM_VISITOR_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
 
 class Function;
 class Class;
 
 template <typename T>
 class Visitor : public ValueObject {
  public:
   virtual ~Visitor() {}
   virtual void Visit(const T& obj) = 0;
 };
 
 typedef Visitor<Function> FunctionVisitor;
 typedef Visitor<Class> ClassVisitor;
 
 class ProgramVisitor : public AllStatic {
  public:
   static void VisitFunctions(FunctionVisitor* visitor);
   static void VisitClasses(ClassVisitor* visitor);
+
+  static void Dedup();
+
+ private:
+  static void ShareMegamorphicBuckets();
+  static void DedupStackMaps();
+  static void DedupPcDescriptors();
+  static void DedupDeoptEntries();
+  static void DedupCodeSourceMaps();
+  static void DedupLists();
+  static void DedupInstructions();
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_PROGRAM_VISITOR_H_