Replaced unary negation by multiplication with -1.

src/parser.cc

 // 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 3179 matching lines @@
 
     // Desugar '+foo' into 'foo*1', this enables the collection of type feedback
     // without any special stub and the multiplication is removed later in
     // Crankshaft's canonicalization pass.
     if (op == Token::ADD) {
       return factory()->NewBinaryOperation(Token::MUL,
                                            expression,
                                            factory()->NewNumberLiteral(1),
                                            position);
     }
+    // The same idea for '-foo' => 'foo*(-1)'.
+    if (op == Token::SUB) {
+      return factory()->NewBinaryOperation(Token::MUL,
+                                           expression,
+                                           factory()->NewNumberLiteral(-1),
+                                           position);
+    }
 
     return factory()->NewUnaryOperation(op, expression, position);
 
   } else if (Token::IsCountOp(op)) {
     op = Next();
     Expression* expression = ParseUnaryExpression(CHECK_OK);
     // Signal a reference error if the expression is an invalid
     // left-hand side expression.  We could report this as a syntax
     // error here but for compatibility with JSC we choose to report the
     // error at runtime.
@@ skipping 2709 matching lines @@
       ASSERT(info()->isolate()->has_pending_exception());
     } else {
       result = ParseProgram();
     }
   }
   info()->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal