[synthetic-shadow] Non-composed bubbling events are not properly filtered

[ekashida]

Description

Only instances of host elements and shadow roots properly filter non-composed events. All other EventTarget instances have access to non-composed events, even when they should not. This includes window, document, and document.documentElement.

This bug affect events that are configured to bubble without being composed. Explicitly speaking, events with this configuration were never supposed to propagate past the immediate shadow root, but this is what is currently happening.

To understand the impact of a fix, we could also try to understand which native events are configured this way.

Non-comprehensive list of native events that bubble but are not composed:

• change
• submit

Steps to Reproduce

https://developer.salesforce.com/docs/component-library/tools/playground/hQ5yrr-hb/1/edit

Browsers Affected

All browsers.

Version

v0.37.0

Possible Solution

Introduce the same non-composed event filtering we do for listeners on host elements and root nodes to wrapped listeners generated by EventTarget.prototype.addEventListener.

[ekashida]

#1138 should probably be addressed at the same time.