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chromium/third_party/blink/web_tests/external/wpt/html/rendering/non-replaced-elements/the-frameset-and-frame-elements/reference/different-writing-modes-ref.html 

<!DOCTYPE html>
<frameset cols="50%,*" rows="50%,*">
 <frame src="../resources/green.html"></frame>
 <frame src="../resources/green.html"></frame>
 <frame></frame>
</frameset>