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

runtime/vm/parser.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_PARSER_H_
 #define VM_PARSER_H_
 
 #include "include/dart_api.h"
 
 #include "vm/ast.h"
@@ skipping 500 matching lines @@
   AstNode* MakeStaticCall(const String& cls_name,
                           const String& func_name,
                           ArgumentListNode* arguments);
   String& Interpolate(ArrayNode* values);
   AstNode* MakeAssertCall(intptr_t begin, intptr_t end);
   AstNode* ThrowTypeError(intptr_t type_pos, const AbstractType& type);
 
   void CheckFunctionIsCallable(intptr_t token_pos, const Function& function);
   void CheckOperatorArity(const MemberDesc& member, Token::Kind operator_token);
 
-  const LocalVariable& GetIncrementTempLocal();
+  const LocalVariable* GetIncrementTempLocal();
   void EnsureExpressionTemp();
   AstNode* CreateAssignmentNode(AstNode* original, AstNode* rhs);
   AstNode* InsertClosureCallNodes(AstNode* condition);
 
   ConstructorCallNode* CreateConstructorCallNode(
       intptr_t token_pos,
       const AbstractTypeArguments& type_arguments,
       const Function& constructor,
       ArgumentListNode* arguments);
 
@@ skipping 35 matching lines @@
 
   // Allocate temporary only once per function.
   LocalVariable* expression_temp_;
 
   DISALLOW_COPY_AND_ASSIGN(Parser);
 };
 
 }  // namespace dart
 
 #endif  // VM_PARSER_H_