Remove unused constructor BinaryOperation(Assignment* compound_assignment).

src/ast.h

 // Copyright 2011 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 1409 matching lines @@
                   Expression* left,
                   Expression* right,
                   int pos)
       : op_(op), left_(left), right_(right), pos_(pos) {
     ASSERT(Token::IsBinaryOp(op));
     right_id_ = (op == Token::AND || op == Token::OR)
         ? static_cast<int>(GetNextId())
         : AstNode::kNoNumber;
   }
 
-  // Create the binary operation corresponding to a compound assignment.
-  explicit BinaryOperation(Assignment* assignment);
-
   DECLARE_NODE_TYPE(BinaryOperation)
 
   virtual bool IsInlineable() const;
 
   virtual bool ResultOverwriteAllowed();
 
   Token::Value op() const { return op_; }
   Expression* left() const { return left_; }
   Expression* right() const { return right_; }
   virtual int position() const { return pos_; }
@@ skipping 737 matching lines @@
 
  private:
   Isolate* isolate_;
   bool stack_overflow_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_