[parser] Fix bug in destructuring binding for catch.

test/mjsunit/regress/regress-5178.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.
 
 assertThrows(() => {
-  new class extends Object {
-    constructor() { (() => delete super[super()])(); }
-  }
+  try { throw {} } catch({a=b, b}) { a+b }

[adamk, 2016/07/12 21:15:22]

Can you also add a test case where we do a hole check but it passes? Something
like:

try { throw {a: 42} } catch ({a, b = a}) { assertEquals(42, b) }

 }, ReferenceError);