Field weights are not migrated

When migrating content and their related content types from D6 to D8, the various field's weights as they are in D6 do not get migrated.

Here are the various changes from D6 to D8 for the field weights of a content type:

• In the Manage display tab:
  • In the Default sub-tab:
    • All the fields are disabled.
    • The fields are not shown in their correct order.
    • Their weights are all set to 0.
  • In the Full, RSS, and Teaser sub-tabs:
    • All the fields are enabled.
    • The fields are not shown in their correct order.
    • Their weights are set, but they are set to the wrong values. It may be that the weight values are assigned to the wrong fields.

  (Some or all of the above may or may not be fixed and/or related to #2278613: Body text display is blank for migrated content types.)

• In the Manage form display tab:
  • The fields are not shown in their correct order.
  • None of the fields have their original D6 weights. The weight numbers start with the weight of the last field +1.
• In the Manage fields tab:
  • The fields are shown in their correct order.
  • The weights are not shown, and so I don't know if they are correct, but I assume so, because all the above items were not in the correct order and did not have the correct weights.

It is possible that some or all of this might be fixed with #2262275: D6->D8 CCK Single On/Off Checkbox, Checkboxes/Radio buttons, and Select formatters.