if (mSourceVariable) { rv = aVariables.Add(mSourceVariable); if (NS_FAILED(rv)) return rv; }
rv = aVariables.Add(mContentVariable); if (NS_FAILED(rv)) return rv;
RDFPropertyTestNode::GetAncestorVariables(VariableSet& aVariables) const{    nsresult rv;    if (mSourceVariable) {        rv = aVariables.Add(mSourceVariable);        if (NS_FAILED(rv)) return rv;    }    if (mTargetVariable) {        rv = aVariables.Add(mTargetVariable);        if (NS_FAILED(rv)) return rv;    }    return TestNode::GetAncestorVariables(aVariables);}