Display table header groups at the top of each page
FF, IE and Edge all repeat a table header group at the top of each printed page.
This area is underspecified but after some discussion in the bug we agreed to
repeat the header group if it has break-inside:avoid. We make this the default
style for theads when printing.
BUG=
24826
Committed:
https://crrev.com/81c0fc6d4e08e4e2bb4eb8a42747f21b13303616
Cr-Commit-Position: refs/heads/master@{#397915}