Clarify the destructuring syntax

[Егор Николаев]

1. Should the AssignmentExpression of DestructuringAssignment always to be
the Object type?
```javascript
let {length} = "123";
assert(length, 3);
```
Is this valid?

If it is:
2. Should the result of Get(obj, name) always be the Object type if
DestructuringAssignmentTarget is an ObjectLiteral or an ArrayLiteral?
According the spec 12.14.5.4 step 4.b this expression is invalid:
```javascript
let {text: {length}} = {text: "123"};
assert(length, 3);
```
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20140411/9c91f399/attachment.html>