nsICSSRule*  rule = (nsICSSRule*)aElement;  if (nsnull != rule) { rule->SetStyleSheet((nsICSSStyleSheet*)aSheet);
if (aRule) { aRule->SetStyleSheet((nsICSSStyleSheet*)aSheet);
static PRBool SetStyleSheetReference(nsISupports* aElement, void* aSheet){  nsICSSRule*  rule = (nsICSSRule*)aElement;  if (nsnull != rule) {    rule->SetStyleSheet((nsICSSStyleSheet*)aSheet);  }  return PR_TRUE;}