Bug 1978234 - Use simpler software downscale fallback. r=ahale
Differential Revision:
https://phabricator.services.mozilla.com/D257942
<html xmlns="http://www.w3.org/1999/xhtml" contenteditable="true" style="user-select: all;"><sub>x</sub><script>
function boom()
{
window.getSelection().removeAllRanges();
var r = document.createRange();
r.setStart(document.documentElement, 0);
r.setEnd(document.documentElement, 0);
window.getSelection().addRange(r);
document.execCommand("subscript", false, null);
document.execCommand("insertText", false, "y");
}
window.addEventListener("load", boom, false);
</script></html>
