**Description**

For a DAG that looks like this:

```
A >> B
```

If A fails, B goes into "upstream_failed" state. If a user then marks A "success", B will remain in "upstream_failed" state. It will not automatically start running. This scenario often happens if the failure of A is dealt with outside of Airflow and the user does not want Airflow to run A again. But he usually expect Airflow to run B after A is marked "success".

**Use case / motivation**

After A is marked "success", its downstream tasks B should be cleared automatically and get ready to be scheduled. To avoid changing this behaviour completely, there can be a toggle button next to "Success" that lets the user decide if he wants Airflow to automatically clear downstream tasks that are in "upstream_failed" state.
airflow/www/views.py
]
    add_columns = edit_columns = [
        'conn_id',
        'conn_type',
        'description',
        'host',
        'schema',
        'login',
        'password',
        'port',
        'extra',
    ] + extra_fields
    add_form = edit_form = ConnectionForm
    add_template = 'airflow/conn_create.html'
    edit_template = 'airflow/conn_edit.html'
    add_widget = ConnectionFormWidget
    edit_widget = ConnectionFormWidget
    base_order = ('conn_id', 'asc')
    @action('muldelete', 'Delete', 'Are you sure you want to delete selected records?', single=False)
    @auth.has_access(
        [
            (permissions.ACTION_CAN_EDIT, permissions.RESOURCE_DAG),
        ]
    )
    def action_muldelete(self, items):
        """Multiple delete."""
        self.datamodel.delete_all(items)
        self.update_redirect()
        return redirect(self.get_redirect())
    def process_form(self, form, is_created):