As a hiring manager that gives take home tests rather than testing on site, I feel on balance it gives a better idea of what they're capable of than a barrage of on site tests & technical questions. Given the option of spending half a day on site and half a day at home coding, are you saying you'd prefer that over a full day including half a day of whiteboard and programming with people watching what you do?
There isn't a correct answer I guess, nothing will suite everyone.
It probably won't affect the review process, but it will at least make targeting both browsers from a dev perspective potentially (hopefully!) trivial.
"On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity."
Often the problem being solved by this sort of thing isn't directly about making it easier to work with a language, but making it easier to hire developers. The hiring pool for developers who are very good with PHP is much much larger than a lot of other languages simply by virtue of it being an easy language to get started with.
This is also why Facebook has spent so much time and effort on things like HHVM and Hack.