Replaced unary negation by multiplication with -1.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index df568ef1bbb5962a91c3c3c925da42eee04f2037..aa83969e99977ac61b9e12adc5427a74ff8c0851 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3197,6 +3197,13 @@ Expression* Parser::ParseUnaryExpression(bool* ok) {
                                            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);