Migrate all existing user() usage to element.user()

[lannka]

For #6415

[rudygalfi]

@tiendt Just wanted to confirm: Is this closed by #10858 or is this still other tasks pending?

[tiendt]

@rudygalfi I still have another task pending!

[rudygalfi]

@zhouyx I think we should schedule this soon. Do you have an estimate on the size of effort required?

[ampprojectbot]

This issue hasn't been updated in awhile. @zhouyx Do you have any updates?

[lannka]

Let's bump its priority after the AMP Conf

[zhouyx]

This is a bigger of a change than I expected. The most difficult part is to handle helper function where there's no instance of element. cc @jeffjose on the prioritization.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.