Fix non-symbolic children lookup of fixity declaration
The fix for #23664 (closed) did not correctly account for non-symbolic names when looking up children of a given parent. This one-line fix changes that. Fixes #24037 (closed).
The fix for #23664 (closed) did not correctly account for non-symbolic names when looking up children of a given parent. This one-line fix changes that. Fixes #24037 (closed).