Add support to drag and drop files

[jschfflr]

Now that support for drag and drop operations landed, it would be great to add an api to drag and drop files.

[jschfflr]

@danparksf Do you want to take a look at this?

[danpark-salesforce]

@jschfflr will pass for now, thanks for asking.

[jschfflr]

@danparksf No problem, I'll take care if this. Looks like we need a Chromium change to allow this feature after all...

[stale]

We're marking this issue as unconfirmed because it has not had recent activity and we weren't able to confirm it yet. It will be closed if no further activity occurs within the next 30 days.

[stale]

We are closing this issue. If the issue still persists in the latest version of Puppeteer, please reopen the issue and update the description. We will try our best to accomodate it!