parse: look for bytes whenever possible
parse: look for bytes whenever possible

name              old time/op    new time/op    delta
Parse/Empty-4       1.56µs ± 3%    1.58µs ± 5%    ~            (p=0.234 n=9+10)
Parse/Comment-4     1.91µs ± 4%    1.87µs ± 3%  -2.01%         (p=0.041 n=9+10)
Parse/LongLit-4     7.32µs ± 4%    6.95µs ± 1%  -5.17%         (p=0.000 n=10+9)
Parse/Cmds-4        26.5µs ± 2%    26.1µs ± 2%  -1.55%         (p=0.010 n=10+9)
Parse/Quoted-4      8.98µs ± 4%    8.82µs ± 2%  -1.82%        (p=0.019 n=10+10)
Parse/Block-4       14.1µs ± 4%    13.9µs ± 2%    ~           (p=0.225 n=10+10)
Parse/IfStmt-4      12.6µs ± 3%    12.2µs ± 5%  -3.45%        (p=0.002 n=10+10)
Parse/ForStmt-4     13.4µs ± 5%    13.1µs ± 5%  -2.44%        (p=0.043 n=10+10)
Parse/CmdSubst-4    14.6µs ± 1%    14.7µs ± 5%    ~            (p=0.720 n=9+10)
Parse/Binary-4      10.9µs ± 4%    10.7µs ± 2%  -1.82%         (p=0.017 n=10+9)
Parse/Redirect-4    10.7µs ± 1%    10.7µs ± 4%    ~             (p=0.249 n=9+9)

No changes in allocs.

mvdan/sh,mvdan/sh,mvdan/sh,mvdan/sh