Handle invalidating cache if dependency is a globAsset

[DeMoorJasper]

Duplicate of #1414

This is needed to properly invalidate and cache styl files as they allow glob requires.

But I kind of messed up a rebase, so here is a clean version

Closes #1546

[fathyb]

nit-pick: use Promise.all for better perf:

if (isGlob(filename)) {
    let files = await glob(filename, {
        strict: true,
        nodir: true
    });

    mtime = (
        await Promise.all(
            files.map(file =>
                fs.stat(file).then(({mtime}) => mtime.getTime())
            )
        )
    ).reduce((a, b) => Math.max(a, b), 0)
}

[DeMoorJasper]

I'll change it

[devongovett]

Maybe it would simplify things if we just marked all GlobAssets as non-cacheable? That way the cache wouldn't need to have specific logic about them. Alternatively we could use the shouldInvalidate hook in GlobAsset to check that...

Right now we always need to run glob for GlobAssets every time, and that's the expensive part. So if that's the case, we might as well just not cache them at all. WDYT?

[DeMoorJasper]

@devongovett Won't this invalidate the parent asset as well? as the main edit in this PR is dependencies.
Not sure if this would still be faster if the parent asset is a fairly large js file in production mode.

[devongovett]

When you require('./foo/*.js') for example, a virtual file (the GlobAsset) is created which looks something like this:

module.exports = {
  test: require('./foo/test.js'),
  bar: require('./foo/bar.js')
};

That's the "file" that you are needing to invalidate when files are added/removed. So if we just don't cache that at all, it should just work for free. Not sure we would gain anything by caching it since we need to check it every time anyway.

[codecov-io]

Codecov Report

Merging #1417 into master will increase coverage by 1.13%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #1417      +/-   ##
=========================================
+ Coverage   87.96%   89.1%   +1.13%     
=========================================
  Files          80      81       +1     
  Lines        4653    4679      +26     
=========================================
+ Hits         4093    4169      +76     
+ Misses        560     510      -50

Impacted Files	Coverage Δ
src/FSCache.js	98.41% <100%> (+1.74%)	⬆️
src/Parser.js	100% <100%> (ø)	⬆️
src/utils/glob.js	100% <100%> (ø)
src/assets/GlobAsset.js	97.26% <100%> (-1.43%)	⬇️
src/workerfarm/errorUtils.js	82.35% <0%> (-5.89%)	⬇️
src/worker.js	95% <0%> (-5%)	⬇️
src/visitors/dependencies.js	91.45% <0%> (-4.28%)	⬇️
src/Logger.js	95.78% <0%> (-1.06%)	⬇️
src/assets/CoffeeScriptAsset.js	100% <0%> (ø)	⬆️
... and 11 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 83dfa3e...55951bd. Read the comment docs.