[test] Remove useless test code.

test/mjsunit/stack-traces.js

 // Copyright 2009 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 287 matching lines @@
 
 testTraceNativeConstructor(String);  // Does ToString on argument.
 testTraceNativeConstructor(RegExp);  // Does ToString on argument.
 
 // Omitted because QuickSort has builtins object as receiver, and is non-native
 // builtin.
 testOmittedBuiltin(function(){ [thrower, 2].sort(function (a,b) {
                                                      (b < a) - (a < b); });
                    }, "QuickSort");
 
-// Omitted because ADD from runtime.js is non-native builtin.
-testOmittedBuiltin(function(){ thrower + 2; }, "ADD");
-
 var reached = false;
 var error = new Error();
 error.toString = function() { reached = true; };
 error.stack;
 assertFalse(reached);
 
 reached = false;
 error = new Error();
 Array.prototype.push = function(x) { reached = true; };
 Array.prototype.join = function(x) { reached = true; };
@@ skipping 112 matching lines @@
 assertTrue(err.stack.indexOf("prepareStackTrace") != -1);
 
 // Check that the callsite constructor throws.
 
 Error.prepareStackTrace = (e,s) => s;
 var constructor = new Error().stack[0].constructor;
 
 assertThrows(() => constructor.call());
 assertThrows(() => constructor.call(
     null, {}, () => undefined, {valueOf() { return 0 }}, false));