NS_ASSERTION((nsnull == mContent) && (nsnull != aContent), "null ptr");
NS_ENSURE_TRUE(aAttrName && aContent, NS_ERROR_NULL_POINTER);
nsAttributeContent::Init(nsIContent* aContent, PRInt32 aNameSpaceID, nsIAtom* aAttrName){  NS_ASSERTION((nsnull == mContent) && (nsnull != aContent), "null ptr");  mContent = aContent;  NS_IF_RELEASE(mAttrName);  mNameSpaceID = aNameSpaceID;  mAttrName    = aAttrName;  NS_ADDREF(mAttrName);  return NS_OK;}