perf(mangler): allocate data in arena #26382

Job	Run time
Build Linter Benchmark	2m 42s
Benchmark (lexer)	1m 53s
Benchmark (parser)	1m 50s
Benchmark (transformer)	2m 7s
Benchmark (isolated_declarations)	2m 12s
Benchmark (semantic)	1m 55s
Benchmark (minifier)	2m 31s
Benchmark (codegen)	3m 57s
Benchmark linter (0)	3m 21s
Benchmark linter (1)	1m 57s
Upload benchmarks	26s
	24m 51s

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