refactor(transformer/arrow-functions): add TODO comments #25924

Job	Run time
Benchmark (lexer)	1m 30s
Build Linter Benchmark	2m 45s
Benchmark (parser)	1m 41s
Benchmark (transformer)	2m 26s
Benchmark (isolated_declarations)	2m 4s
Benchmark (semantic)	1m 56s
Benchmark (minifier)	2m 16s
Benchmark (codegen)	2m 14s
Benchmark linter (0)	3m 5s
Benchmark linter (1)	1m 35s
Upload benchmarks	16s
	21m 48s

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