Remove runtime flags for sloppy mode block scoping features

test/mjsunit/es6/block-non-strict-errors.js

-// Copyright 2014 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: --no-harmony-sloppy-let --no-harmony-sloppy-function
-// Flags: --no-harmony-sloppy
-
-function CheckError(source) {
-  var exception = null;
-  try {
-    eval(source);
-  } catch (e) {
-    exception = e;
-  }
-  assertNotNull(exception);
-  assertEquals(
-      "Block-scoped declarations (let, const, function, class) not yet supported outside strict mode",
-      exception.message);
-}
-
-
-function CheckOk(source) {
-  eval(source);
-}
-
-CheckError("let x = 1;");
-CheckError("{ let x = 1; }");
-CheckError("function f() { let x = 1; }");
-CheckError("for (let x = 1; x < 1; x++) {}");
-CheckError("for (let x of []) {}");
-CheckError("for (let x in []) {}");
-CheckError("class C {}");
-CheckError("class C extends Array {}");
-CheckError("(class {});");
-CheckError("(class extends Array {});");
-CheckError("(class C {});");
-CheckError("(class C exends Array {});");
-
-CheckOk("let = 1;");
-CheckOk("{ let = 1; }");
-CheckOk("function f() { let = 1; }");
-CheckOk("for (let = 1; let < 1; let++) {}");