if (node instanceof CssTree.Term
&& CssPropertyPartType.URI == propertyPartType(node)) {
CssTree term = (CssTree.Term) node;
CssTree.CssLiteral content =
(CssTree.CssLiteral) term.children().get(0);
if (content instanceof CssTree.Substitution) {
return true; // Handled by later pass.
}
Name propertyPart = propertyPart(node);