nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2);
nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2, aChangedPseudoClass);
PresShell::ContentStatesChanged(nsIDocument* aDocument,                                nsIContent* aContent1,                                nsIContent* aContent2){  WillCauseReflow();  nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2);  VERIFY_STYLE_TREE;  DidCauseReflow();  return rv;}