We do no simplification of arguments to function calls. This includes
close, which appears in the AST as a normal CallExpr.

-- a.cue --
y: close({a: int, b: {c: string}}) & {a: 4, b: {c: "hi"}}
z: close({a: int, b: {c: string}} & {a: 4, b: {c: "hi"}})
-- out/trim --
== a.cue
y: close({a: int, b: {c: string}}) & {a: 4, b: {c: "hi"}}
z: close({a: int, b: {c: string}} & {a: 4, b: {c: "hi"}})
