IR: add more instructions

* MaybeWrap
 * TestErr
 * UnwrapErrCode
 * UnwrapErrPayload
 * ErrUnionTypeChild
 * ErrWrapCode
 * ErrWrapPayload
12fcbecbf8Andrew Kelley committed on 12/17/2016, 9:16:17 PMparent3a3cc7b
8 files changedLine totals unavailable