if(arr) now a warning

[Martin Nowak via Digitalmars-d]

On 04/10/2015 07:28 PM, Steven Schveighoffer wrote:
>> Also empty should work for AAs.
> 
> How should "abc".front work? Do you want to move unicode decoding of
> char and wchar arrays into object.d?

We already have unicode decoding in druntime, the old and slow version
though. Wouldn't cost much to move those 2 functions.
Also we now have core.internal for more contrived stuff, works like this.
https://github.com/D-Programming-Language/druntime/blob/master/src/object.di#L697