The public suffix list scanner's utf8encode()'s main loop always
worked out whether a character is a hex digit, even when it didn't
need to know. Package the computation in a lambda and only test it
when it is needed. Also assert non-empty input generates non-empty
output.
Change-Id: Iaf48aad382624e421cea9c9cdb8bba5fc47b1596
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Ievgenii Meshcheriakov <ievgenii.meshcheriakov@qt.io>
755b0aa681