Repeating Thead Multiple Tables

crbug.com/621258: Don't let repeating headers overlap on pages that contain two tables.

| Col 1 | | --- | | Te | xt | | Te | xt | | Te | xt | | Te | xt | | Te | xt | | Te | xt | | Te | xt | | Te | xt | | Te | xt |

| 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 |