What is the contraction for Jon's?

The proper noun form Jon's may be a contraction, or it may be a possessive noun. The contraction can mean "Jon is" or "Jon has."

Jon's missing - Jon is missing (contraction)
Jon's left town - Jon has left town (contraction)
Jon's been married twice - Jon has been married twice (contraction)

Jon's car will not start. (possessive, his car)
Jon's success came at a price (possessive, his success)