UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Steps to reproduce the problem:
1. Select a directory via webkitdirectory with lot of file (size doesn't matter)
2. Click the upload button
3. The website is stuck with no feedback that the file loading is still in progress

I just uploaded my downloads folder with a more than 10K files (we have clients that do that).

What is the expected behavior?
- Core should indicate / progress that it is enumerating the files to upload
- Events should be added for the developer that the enumeration has started / ended so that we can inform the end user that the browser is preparing the files (I can add a event on click to select a upload, but i cant detect that the user canceled the dialog)

What went wrong?
- The website is stuck and the user is waiting for a minute or more thill it works again without any feedback from chrome, and developers can't handle it.

Did this work before? No 

Chrome version: 67.0.3396.99  Channel: n/a
OS Version: OS X 10.13.4
Flash Version: