Shadydom enforces capturing phase in IE 11

[attilapuskas]

Description

If the event listeners are added via properties (like in GWT for example) then using shadydom in IE 11 could cause several issues because the events will use the capturing phase logic and not the default/expected bubbling phase.

Live Demo

https://jsbin.com/tojafuvowo/1/edit?html,js,output

Steps to Reproduce

1. Create "outer" and "inner" element so that inner is a descendant of outer.
2. Add event listener using properties, for example onmousedown.

Expected Results

Triggering a related event should be dispatched first on the children if that was the target.

Actual Results

The event is dispatched first on parent (capturing phase).

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari 9
• Safari 8
• IE 11

Versions

• webcomponents/shadydom: v1.1.0 and above (it is not reproducible in 1.0.14)

[attilapuskas]

Strange thing but removing the empty object from that line solves the issue. As I've debugged it the optionsOrCapture is handled properly in the patch-events.js but still IE 11 somehow uses capturing phase if it is used.

The following test should be ok for that. I'll create a PR if I found time for that soon.

    test('should use bubbling phase for event listeners added via properties', function () {
      const parent = document.createElement('div');
      parent.id="parent";
      document.body.appendChild(parent);
      const child = document.createElement('div');
      child.id="child";
      parent.appendChild(child);

      const parentMouseDownSpy = sinon.spy();
      const childMouseDownSpy = sinon.spy();

      parent.onmousedown = parentMouseDownSpy;
      child.onmousedown = childMouseDownSpy;

      child.dispatchEvent(new MouseEvent('mousedown', { bubbles: true, composed: true }));

      assert.isTrue(childMouseDownSpy.calledBefore(parentMouseDownSpy), 'Event handler on child should be called first');
    });

[web-padawan]

Yeah, that empty object forces capture phase in browsers not supporting event listener options.
Looks like the intervention for passive event listeners strikes again.