tests/test-check-jshint.t

perf: use the `perf--` prefix for perf command

This is the one command namespace where they should not be any ambiguity about
command that should be in it. The perf extensions is only adding performance
related command.

so this is a good ground to start putting dash folding to the tests.

Differential Revision: https://phab.mercurial-scm.org/D9516

#require test-repo jshint hg10

  $ . "$TESTDIR/helpers-testrepo.sh"

run jshint on all tracked files ending in .js except vendored dependencies

  $ cd "`dirname "$TESTDIR"`"

  $ testrepohg locate 'set:**.js' \
  > 2>/dev/null \
  > | xargs jshint