Remove always-on --harmony-rest-parameters flag

test/mjsunit/strong/function-arity.js

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --strong-mode --harmony-reflect
-// Flags: --harmony-rest-parameters --allow-natives-syntax
+// Flags: --allow-natives-syntax
 
 'use strict';
 
 
 function generateArguments(n, prefix) {
   let a = [];
   if (prefix) {
     a.push(prefix);
   }
   for (let i = 0; i < n; i++) {
@@ skipping 315 matching lines @@
           if (argumentCount < parameterCount) {
             assertThrows(code, TypeError);
           } else {
             assertDoesNotThrow(code);
           }
         }
       }
     }
   }
 })();