syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // stack entry than `from_dfn`. We have to update their depth with our transitive
context_before:         // that remains in the provisional cache must be dependent on some older
context_after:         // depth in that case or else it would be referring to some popped note.