Alias for long exported names

One of my takeaways from reading the documentation on externs vs exports was that externs are discouraged as a way to prevent mangling of your own api/data model.

It made sense to me that exports via `obj['somePropertyName']` might be more optimized since the compiler can use internal aliases rather than carrying forward the full name everywhere.

I decided to test this out with the example below:

```
function createPersonModel(data) {
var fullName = data['info']['firstNameProperty'] + data['info']['lastNameProperty'];
var fullNameReverse = data['info']['lastNameProperty'] + data['info']['firstNameProperty'];

console.log(fullName);
console.log(fullNameReverse);
}

createPersonModel(anObjectFromAnApi);
```

Let's just assume this is a deep object returned from an api, and I am using `['']` notation to prevent mangling.

Based on what I read in the documentation I was expecting the repeated property references to be aliased?

Instead the code compiled to the following:

```
var a=anObjectFromAnApi.info.lastNameProperty+anObjectFromAnApi.info.firstNameProperty;
console.log(anObjectFromAnApi.info.firstNameProperty+anObjectFromAnApi.info.lastNameProperty);
console.log(a);
```
Isn't there an opportunity here to assign `anObjectFromAnApi.info.lastNameProperty` and `anObjectFromAnApi.info.lastNameProperty` to single character aliases?

I also tried exaggerating this by adding several more references to these properties to see if an alias would be introduced. The behavior was the same though.

Am I misunderstanding the point about aliasing of exports when compared to externs?