CMS: Jump to field if validation error

[froog]

In Model Admin (or Page, or anywhere where there is a form), if you have a field that has a validation error and is below the fold (ie; you'd need to scroll to see it), it won't scroll to that field with the error.

This is a problem as it means the user might think that the form has been successfully saved where in fact it hasn't.

There is scroll related code in LeftAndMain.EditForm.js (saveFieldFocus & restoreFieldFocus) but this is to scroll to the last focused field.

[sachajudd]

Related: silverstripe/silverstripe-cms#2081