Function init_one_field 

pub fn init_one_field(
    inst: &Value,
    name: &str,
    thunk: &Value,
    name_anon: bool,
) -> Result<(), String>

Evaluate ONE instance-field initializer thunk and install the result on inst.

Shared by the base-class path (init_fields) and the derived-class path that runs after super(...); the two used to be separate loops, and only the first canonicalized an array-index key.

name_anon carries 15.7.10’s NamedEvaluation: class C { f = function(){} } gives the function the name f. It is decided by the compiler from the syntax, never from the value.