Braces with single-line if blocks

In point [16.1](https://github.com/airbnb/javascript/tree/master/#functions) you state the two block possibilities when it comes to in-line if blocks. These are:

```
if (test) return false;

if (test) {
return false;
}
```

Is there any preference to use one or the other?

Personally, I use the first one only at the top of a function, when I have to verify trivial preconditions. (i.e. `if (!name) return 'Name is required';`.

Review point 16.1 in the linked Functions section and the existing examples for single-line if blocks. Determine whether the guide should express a preference between the two forms, then update that guidance if a maintainer decision is reached. Done means the style guide gives an unambiguous answer to this question.

Written by the indexing model from the issue text.