syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // that remains in the provisional cache must be dependent on some older
context_before:         // Subtle: when we complete working on the DFN `from_dfn`, anything
context_after:         // stack entry than `from_dfn`. We have to update their depth with our transitive