Make utf8 validity check function self-contained.
Make utf8 validity check function self-contained.

etsy/Hound,etsy/Hound,0xmohit/hound,gwindes/Hound,Kareo/Hound,etsy/Hound,Kareo/Hound,gwindes/Hound,0xmohit/hound,gwindes/Hound,sstarcher/Hound,Kareo/Hound,sstarcher/Hound,0xmohit/hound,sstarcher/Hound,etsy/Hound,gwindes/Hound,Kareo/Hound,sstarcher/Hound,0xmohit/hound,Kareo/Hound