mShell->StyleSet()->ClearStyleData(this);
nsCOMPtr<nsIStyleSet> set; mShell->GetStyleSet(getter_AddRefs(set)); set->ClearStyleData(this, nsnull, nsnull);
nsPresContext::ClearStyleDataAndReflow(){  if (mShell) {    // Clear out all our style data.    mShell->StyleSet()->ClearStyleData(this);    // Force a reflow of the root frame    // XXX We really should only do a reflow if a preference that affects    // formatting changed, e.g., a font change. If it's just a color change    // then we only need to repaint...    mShell->StyleChangeReflow();  }}