Remove all harmony runtime flags which shipped in M51

test/mjsunit/es6/legacy-subclassing.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: --noharmony-species
-
-// Before Symbol.species was added, ArrayBuffer subclasses constructed
-// ArrayBuffers, and Array subclasses constructed Arrays, but TypedArray and
-// Promise subclasses constructed an instance of the subclass.
-
-'use strict';
-
-assertEquals(undefined, Symbol.species);
-
-class MyArray extends Array { }
-let myArray = new MyArray();
-assertEquals(MyArray, myArray.constructor);
-assertEquals(Array, myArray.map(x => x + 1).constructor);
-assertEquals(Array, myArray.concat().constructor);
-
-class MyUint8Array extends Uint8Array { }
-Object.defineProperty(MyUint8Array.prototype, "BYTES_PER_ELEMENT", {value: 1});
-let myTypedArray = new MyUint8Array(3);
-assertEquals(MyUint8Array, myTypedArray.constructor);
-assertEquals(MyUint8Array, myTypedArray.map(x => x + 1).constructor);
-
-class MyArrayBuffer extends ArrayBuffer { }
-let myBuffer = new MyArrayBuffer(0);
-assertEquals(MyArrayBuffer, myBuffer.constructor);
-assertEquals(ArrayBuffer, myBuffer.slice().constructor);
-
-class MyPromise extends Promise { }
-let myPromise = new MyPromise(() => {});
-assertEquals(MyPromise, myPromise.constructor);
-assertEquals(MyPromise, myPromise.then().constructor);
-
-// However, subarray instantiates members of the parent class
-assertEquals(Uint8Array, myTypedArray.subarray(1).constructor);