Remove arguments arity check in mjsunit because it vastly slows down the tests.

test/mjsunit/mjsunit.js

 // Copyright 2008 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 213 matching lines @@
       }
       return true;
     }
     if (objectClass == "String" || objectClass == "Number" ||
       objectClass == "Boolean" || objectClass == "Date") {
       if (a.valueOf() !== b.valueOf()) return false;
     }
     return deepObjectEquals(a, b);
   }
 
-  function checkArity(args, arity, name) {
-    if (args.length < arity) {
-      fail(PrettyPrint(arity), args.length,
-           name + " requires " + arity + " or more arguments");
-    }
-  }
-
   assertSame = function assertSame(expected, found, name_opt) {
-    checkArity(arguments, 2, "assertSame");
-
     // TODO(mstarzinger): We should think about using Harmony's egal operator
     // or the function equivalent Object.is() here.
     if (found === expected) {
       if (expected !== 0 || (1 / expected) == (1 / found)) return;
     } else if ((expected !== expected) && (found !== found)) {
       return;
     }
     fail(PrettyPrint(expected), found, name_opt);
   };
 
 
   assertEquals = function assertEquals(expected, found, name_opt) {
-    checkArity(arguments, 2, "assertEquals");
-
     if (!deepEquals(found, expected)) {
       fail(PrettyPrint(expected), found, name_opt);
     }
   };
 
 
   assertEqualsDelta =
       function assertEqualsDelta(expected, found, delta, name_opt) {
     assertTrue(Math.abs(expected - found) <= delta, name_opt);
   };
@@ skipping 131 matching lines @@
     if (sync_opt === undefined) sync_opt = "";
     assertTrue(OptimizationStatus(fun, sync_opt) != 1, name_opt);
   }
 
   assertOptimized = function assertOptimized(fun, sync_opt, name_opt) {
     if (sync_opt === undefined) sync_opt = "";
     assertTrue(OptimizationStatus(fun, sync_opt) != 2, name_opt);
   }
 
 })();