buffer: optimize byteLength for short strings
M2
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='four_bytes' 5.08 % ±27.63% ±43.80% ±75.96%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='one_byte' 9.92 % ±43.25% ±67.27% ±112.98%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='three_bytes' 12.47 % ±31.61% ±49.92% ±86.02%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='two_bytes' 34.02 % ±52.38% ±76.67% ±116.30%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='four_bytes' ** 82.80 % ±52.56% ±76.65% ±115.59%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='one_byte' 5.31 % ±48.31% ±70.43% ±106.17%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='three_bytes' ** 60.17 % ±34.55% ±50.81% ±77.68%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='two_bytes' ** 68.52 % ±32.32% ±48.53% ±76.85%