[es8] More spec compliant syntactic tail calls implementation.

test/message/syntactic-tail-call-in-for-of.js

 // 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
 
 function f() {
   return 1;
 }
 
 function g() {
   for (var v of [1, 2, 3]) {
-    return continue f();
+    return continue f()  ;
   }
 }