object literal destructuring

[dariajung]

From Rado:

As discussed object literal destructuring cannot be handled well, because it contains a property 
declaration or access (things we rename) and a local variable expression (something we leave to
 uglifyJS).

var {a} = foo;

is sugar for

var a = foo.a;
which should be renamed to

var a = foo.$
but there is no way to do that while keeping the sugar.

Similarly for property declaration {a} is sugar for {a: a} and we rename that to {$: a}. 
For now I suggest we detect these and throw an error.