Store pointer instead of reference to LocalVariable in ast and flow graph.

runtime/vm/ast_printer.h

 // Copyright (c) 2011, 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_AST_PRINTER_H_
 #define VM_AST_PRINTER_H_
 
 #include "vm/ast.h"
 #include "vm/growable_array.h"
 
@@ skipping 13 matching lines @@
 #define DEFINE_VISITOR_FUNCTION(type, name)                                    \
   virtual void Visit##type(type* node);
 NODE_LIST(DEFINE_VISITOR_FUNCTION)
 #undef DEFINE_VISITOR_FUNCTION
 
  private:
   AstPrinter();
   ~AstPrinter();
 
   void VisitGenericAstNode(AstNode* node);
-  void VisitGenericLocalNode(AstNode* node, const LocalVariable& local);
+  void VisitGenericLocalNode(AstNode* node, const LocalVariable* local);
   void VisitGenericFieldNode(AstNode* node, const Field& field);
 
   DISALLOW_COPY_AND_ASSIGN(AstPrinter);
 };
 
 }  // namespace dart
 
 #endif  // VM_AST_PRINTER_H_