Merge branch 'form-tweaks' of https://github.com/twbs/bootstrap into form-tweaks

diff --cc docs/4.0/migration.md
index 4779d1b4d1489f3d14dfc4ca930c4b64d4e265ee,5d5343ca9160d52d1d3773971e5cef1f937397b1..f1e6b9fe2d06ac85a69ae099101b3da99edb18da
--- 1/docs/4.0/migration.md
--- 2/docs/4.0/migration.md
+++ b/docs/4.0/migration.md
@@@ -103,10 -103,9 +103,11 @@@ New to Bootstrap 4 is the [Reboot]({{ s
    - Dropped the `.form-horizontal` class requirement.
    - `.form-group` no longer applies styles from the `.row` via mixin, so `.row` is now required for horizontal grid layouts (e.g., `<div class="form-group row">`).
    - Added new `.form-control-label` class to vertically center labels with `.form-control`s.
 +  - Added new `.form-row` for compact form layouts with the grid classes (swap your `.row` for a `.form-row` and go).
  - Added custom forms support (for checkboxes, radios, selects, and file inputs).
- - Renamed `.has-error` to `.has-danger`.
 +- Added HTML5 form validation support via CSS's `:invalid` and `:valid` pseudo-classes.
+ - Renamed `.has-error` to `.has-danger`.
+ - Renamed `.form-control-static` to `.form-control-plaintext`.
  
  ### Buttons