Fixing some code declarations

So I'm using php-diff in a project of mine, and I ran a php-lint like software called xref, https://github.com/gariev/xref , and it pointed me to two different possible bugs in the php-diff code. I've tested this change as best as I can, but I'm not 100% sure I was ever even hitting this code.

I'm submitting this too you in the hopes of you either telling me that no these aren't bugs, or yes they are.

Either way, I just want to say thanks, and I appreciate you putting this library together in the first place.

Cheers,