Fix 'eval' in class extends clauses to be always-strict

test/mjsunit/regress/regress-4970.js

Index: test/mjsunit/regress/regress-4970.js
diff --git a/test/mjsunit/regress/regress-crbug-513471.js b/test/mjsunit/regress/regress-4970.js
similarity index 60%
copy from test/mjsunit/regress/regress-crbug-513471.js
copy to test/mjsunit/regress/regress-4970.js
index 48c793e512315284ddf218f8847d9c357280fe95..da0033b34f57891945eea6f97ee8c760956dcd36 100644
--- a/test/mjsunit/regress/regress-crbug-513471.js
+++ b/test/mjsunit/regress/regress-4970.js
@@ -1,10 +1,15 @@
 // 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: --allow-natives-syntax
 
-var g = (function*(){});
-var f = g();
+function g() {
+  var f;
+  class C extends eval("f = () => delete C; Array") {}
+  f();
+}
+
+assertThrows(g, SyntaxError);
 %OptimizeFunctionOnNextCall(g);
-f.next();
+assertThrows(g, SyntaxError);