fixed: do not set readonly property.

[cbbfcd]

fixed: [#191 ]

refer to: hyperapp

Please describe the changes this PR makes and why it should be merged:
bug fixed.
Status

• Code changes have been tested against prettier, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

Semantic versioning classification:

• This PR changes the codebase
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
  • This PR changes the internal workings with no modifications to the external API (bug fixes, performance improvements)
• This PR only includes non-code changes, like changes to documentation, README, etc.

[aidenybai]

LGTM, thank you!