Change babel-register default ignore to cwd content.

[loganfsmyth]

Q	A
Patch: Bug Fix?	Y, from #5487
Major: Breaking Change?	N
Minor: New Feature?	N
Deprecations?
Spec Compliancy?
Tests Added/Pass?
Fixed Tickets
License	MIT
Doc PR
Dependency Changes

I realized that I regressed this behavior from https://github.com/babel/babel/pull/5487/files#diff-75a0292ed78043766c2d5564edd84ad2L92

The behavior of babel-register in 6.x is equivalent to:

function shouldIgnore(filename){
  return (isInAnyNodeModules(filename) && !isInCwd(filename)) ||
    isInCwdNodeModules(filename);
}

assuming I'm covering all the edge cases here finally. The relative directory logic that was there before was pretty confusing and I misunderstood it the first time.

Currently I broke it by making it

function shouldIgnore(filename){
  return isInCwdNodeModules(filename);
}

which will try to compile node_modules that are not nested in the working directory, like things that are symlinked.

[mention-bot]

@loganfsmyth, thanks for your PR! By analyzing the history of the files in this pull request, we identified @hzoo, @existentialism and @forivall to be potential reviewers.