path: improve posixSplitPath performance
Instead of slicing the first element off of the matches, manually build the array. This improves performance of the following path.posix functions:
- basename
- path/basename.js type=win32 n=1000000: ./node: 847760 /usr/local/bin/node: 829710 .. 2.18%
- path/basename.js type=posix n=1000000: ./node: 989290 /usr/local/bin/node: 847820 . 21.55%
- extname
- path/extname.js type=win32 n=1000000: ./node: 2385400 /usr/local/bin/node: 2451800 . -2.71%
- path/extname.js type=posix n=1000000: ./node: 3379700 /usr/local/bin/node: 2113500 . 70.64%
- dirname
- path/dirname.js type=win32 n=1000000: ./node: 1699600 /usr/local/bin/node: 1706700 . -0.42%
- path/dirname.js type=posix n=1000000: ./node: 2038700 /usr/local/bin/node: 1704300 . 21.99%
- parse
- path/parse.js type=win32 n=1000000: ./node: 1907900 /usr/local/bin/node: 1886300 .. 1.15%
- path/parse.js type=posix n=1000000: ./node: 1923400 /usr/local/bin/node: 1616800 . 22.79%