Add soft-deopt for uninitialized assignment

src/ast.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2078 matching lines @@
 
   // This check relies on the definition order of token in token.h.
   bool is_compound() const { return op() > Token::ASSIGN; }
 
   BailoutId AssignmentId() const { return assignment_id_; }
 
   // Type feedback information.
   TypeFeedbackId AssignmentFeedbackId() { return reuse(id()); }
   void RecordTypeFeedback(TypeFeedbackOracle* oracle, Zone* zone);
   virtual bool IsMonomorphic() { return is_monomorphic_; }
+  bool IsUninitialized() { return is_uninitialized_; }
   virtual SmallMapList* GetReceiverTypes() { return &receiver_types_; }
   virtual KeyedAccessStoreMode GetStoreMode() {
     return store_mode_;
   }
 
  protected:
   Assignment(Isolate* isolate,
              Token::Value op,
              Expression* target,
              Expression* value,
@@ skipping 10 matching lines @@
 
  private:
   Token::Value op_;
   Expression* target_;
   Expression* value_;
   int pos_;
   BinaryOperation* binary_operation_;
   const BailoutId assignment_id_;
 
   bool is_monomorphic_ : 1;
+  bool is_uninitialized_ : 1;
   KeyedAccessStoreMode store_mode_ : 5;  // Windows treats as signed,
                                          // must have extra bit.
   SmallMapList receiver_types_;
 };
 
 
 class Yield: public Expression {
  public:
   DECLARE_NODE_TYPE(Yield)
 
@@ skipping 1079 matching lines @@
  private:
   Isolate* isolate_;
   Zone* zone_;
   Visitor visitor_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_