if (NS_SUCCEEDED(result) && (nsnull != mRules)) {
if (NS_SUCCEEDED(result) && mRules) {
CSSMediaRuleImpl::AppendStyleRule(nsICSSRule* aRule){  nsresult result = NS_OK;  if (nsnull == mRules) {    result = NS_NewISupportsArray(&mRules);  }  if (NS_SUCCEEDED(result) && (nsnull != mRules)) {    mRules->AppendElement(aRule);    aRule->SetStyleSheet(mSheet);    if (mSheet) {      mSheet->SetModified(PR_TRUE);    }  }  return result;}