Single Line Cells Repeating Thead Break Inside On Thead Only

crbug.com/24826: A table header group repeats on each page and forces a strut on the rows to achieve it, even when the rows themselves do not force a strut with break-inside:avoid.

Col 1	Col 2
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt
Te	xt