[es8] Remove syntactic tail calls support.

test/message/syntactic-tail-call-in-subclass.js

Index: test/message/syntactic-tail-call-in-subclass.js
diff --git a/test/message/syntactic-tail-call-in-subclass.js b/test/message/syntactic-tail-call-in-subclass.js
deleted file mode 100644
index ab788406d2b844d6eb8f8f9165ea532a1d9fa7a1..0000000000000000000000000000000000000000
--- a/test/message/syntactic-tail-call-in-subclass.js
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2016 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: --harmony-explicit-tailcalls
-"use strict";
-
-function g() {
-  class A {};
-  class B extends A {
-    constructor() {
-      return continue f() ;
-    }
-  }
-}