path: improve normalization performance

[mscdex]

Some results:

 confidence improvement accuracy (*) (**) (***)
path/normalize-posix.js n=10000000 path='.' *** 8.62 % ±1.91% ±2.54% ±3.30%
path/normalize-posix.js n=10000000 path='' *** 8.71 % ±2.00% ±2.67% ±3.49%
path/normalize-posix.js n=10000000 path='/../' *** 7.54 % ±1.97% ±2.64% ±3.46%
path/normalize-posix.js n=10000000 path='/foo' *** 16.09 % ±2.77% ±3.71% ±4.88%
path/normalize-posix.js n=10000000 path='/foo/bar' *** 11.90 % ±1.86% ±2.47% ±3.22%
path/normalize-posix.js n=10000000 path='/foo/bar//baz/asdf/quux/..' *** 9.30 % ±1.98% ±2.64% ±3.45%
path/normalize-win32.js n=10000000 path='.' *** 4.80 % ±1.29% ±1.73% ±2.28%
path/normalize-win32.js n=10000000 path='' *** 4.49 % ±0.94% ±1.26% ±1.66%
path/normalize-win32.js n=10000000 path='C:\\\\..\\\\' 1.48 % ±1.56% ±2.08% ±2.72%
path/normalize-win32.js n=10000000 path='C:\\\\foo' *** 3.33 % ±1.61% ±2.14% ±2.80%
path/normalize-win32.js n=10000000 path='C:\\\\foo\\\\bar' ** 2.26 % ±1.39% ±1.86% ±2.42%
path/normalize-win32.js n=10000000 path='C:\\\\foo\\\\bar\\\\\\\\baz\\\\asdf\\\\quux\\\\..' 0.35 % ±1.28% ±1.71% ±2.24%

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/24834/

[ZYSzys]

Landed in 37d2748.