I concur with those who ask "why do you care?" As has been noted, the missing tabs will have no impact on rendering of the page except, perhaps, to speed that rendering by some tiny fraction of a milisecond, because the rendering agent will need to wait for fewer bytes. :-)

FTR, however, a nitpicky observation about the word "nested" as used here: only the formatting is whacked; not the "nesting." The tags remain properly nested within the sense of .html.