mShell->StyleSet()-> EnableQuirkStyleSheet(mCompatibilityMode == eCompatibility_NavQuirks);
NS_ASSERTION(mShell, "PresShell must be set on PresContext before calling nsPresContext::SetCompatibilityMode"); if (mShell) { nsCOMPtr<nsIStyleSet> set; nsresult rv = mShell->GetStyleSet(getter_AddRefs(set)); if (NS_SUCCEEDED(rv) && set) { set->EnableQuirkStyleSheet((mCompatibilityMode != eCompatibility_Standard) ? PR_TRUE : PR_FALSE); } } return NS_OK;
nsPresContext::SetCompatibilityMode(nsCompatibility aMode){  mCompatibilityMode = aMode;  if (!mShell)    return;  // enable/disable the QuirkSheet  mShell->StyleSet()->    EnableQuirkStyleSheet(mCompatibilityMode == eCompatibility_NavQuirks);}