syntax_data: {"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                 // blocks, so make both of them meet up in a new block.
context_before:                 // The `then` and `else` arms have been lowered into their respective
context_after:                 let join_block = this.cfg.start_new_block();