[strong] Remove all remainders of strong mode

test/mjsunit/strong/destructuring.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: --harmony-destructuring-bind
-// Flags: --strong-mode --allow-natives-syntax
-
-(function() {
-  var f = (function() {
-    "use strong";
-    return function f({ x = function() { return []; } }) { return x(); };
-  })();
-  var a = f({ x: undefined });
-  assertTrue(%IsStrong(a));
-
-  // TODO(rossberg): Loading non-existent properties during destructuring should
-  // not throw in strong mode.
-  assertThrows(function() { f({}); }, TypeError);
-
-  function weakf({ x = function() { return []; } }) { return x(); }
-  a = weakf({});
-  assertFalse(%IsStrong(a));
-
-  function outerf() { return []; }
-  var f2 = (function() {
-    "use strong";
-    return function f2({ x = outerf }) { return x(); };
-  })();
-  a = f2({ x: undefined });
-  assertFalse(%IsStrong(a));
-})();