Delegate does not support shadow dom for Firefox

[michaelw85]

I'm submitting a bug report

Related to: #755

• Library Version:
  2.5.0

Please tell us about your environment:

• Operating System:
  Windows [10]

• Node Version:
  10.15.1

• NPM Version:
  6.10.2

• Browser:
  Firefox 70.0.1 (64-bits)

• Language:
  all

Current behavior:
Clicking nested elements in shadow dom does not trigger click delegate.

In my case this fails for a search input with a search button.

The search button has a click.trigger which should dispatch a custom "on-search" event. This fails due to:

// event-manager.js:7
function findOriginalEventTarget(event) {
  return (event.path && event.path[0]) || (event.deepPath && event.deepPath[0]) || event.target;
}

Result in firefox:
spec-input-search (custom search component containing the search button)

Chrome (which works properly):
button

Reason for failure:
Firefox does not have event.path or deepPath so falls back to target which does not take shadow dom into account.

Proposed solution:
Use composedPath before using fallback to event.target

Expected/desired behavior:
When using shadow dom, nested should handle click delegate properly