Remove dead linear class lookup fallback #941

Job	Run time
Lint	1m 33s
Benchmark	9m 22s
PHP Lint	12s
Test	4m 26s
Benchmark (PR comparison)	0s
Memory Benchmark (PR comparison)	0s
Memory Benchmark	3m 57s
Test	4m 32s
Lint	1m 33s
Benchmark (PR comparison)	-2074s
Benchmark	9m 22s
Memory Benchmark (PR comparison)	-2074s
Memory Benchmark	3m 57s
PHP Lint	12s
Test	4m 33s
Lint	1m 33s
Memory Benchmark (PR comparison)	-226416s
Memory Benchmark	3m 57s
Benchmark	9m 22s
PHP Lint	12s
Benchmark (PR comparison)	-226447s
	-453488s

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