[compiler] Allow optimization of functions with rest parameters.

The parser should have never done this. The AstNumbering takes
care of disabling compilers for certain language constructs.

TBR=rossberg@chromium.org

Review URL: https://codereview.chromium.org/1669523004

Cr-Commit-Position: refs/heads/master@{#33720}

src/parsing/parser.cc

@@ -4400,10 +4400,6 @@ FunctionLiteral* Parser::ParseFunctionLiteral(
   if (should_be_used_once_hint)
     function_literal->set_should_be_used_once_hint();
 
-  if (scope->has_rest_parameter()) {
-    function_literal->set_dont_optimize_reason(kRestParameter);
-  }
-
   if (fni_ != NULL && should_infer_name) fni_->AddFunction(function_literal);
   return function_literal;
 }