crbug.com/620456: A nested table header group repeats on each page.
Col 1
Col 1
Col 2
Te
xt
Te
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Te
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Te
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Te
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Te
xt
Col 1
Col 1
Col 2
Te
xt
Te
xt
Te
xt
Te
xt
Te
xt
Te
xt
Col 1
Col 1
Col 2
Te
xt
Te
xt
Te
xt
Te
xt
Te
xt
Te
xt