Fix build error on Xcode 8.3
Fix build error on Xcode 8.3

This will fix an issue:
> error: cannot force unwrap value of non-optional type 'TextElement'

drmohundro/SWXMLHash,jpsim/SWXMLHash,jpsim/SWXMLHash,drmohundro/SWXMLHash,jpsim/SWXMLHash