Add hasUAVisualTransition attribute to popState and navigate event

[khushalsagar]

Fixes #8782

• At least two implementers are interested (and none opposed):
  • Webkit: positive
  • Gecko: no signal
  • Blink: positive
• Tests are written and can be reviewed and commented upon at:
  • In-progress change here. WPTs assert that the new attribute exists on the events but by design can't test what the value is set to, since that's left to the UA.
• Implementation bugs are filed:
  • Chromium
  • Gecko
  • WebKit
• MDN issue is filed: …

---

/acknowledgements.html ( diff )
/browsing-the-web.html ( diff )
/nav-history-apis.html ( diff )

[domenic]

This unfortunately is not how to specify this behavior.

To do this, you need to properly initialize these attributes at each place that the events are fired. Those places are:

• https://html.spec.whatwg.org/#update-document-for-history-step-application
• https://html.spec.whatwg.org/#inner-navigate-event-firing-algorithm

[khushalsagar]

Done. I wasn't sure what to write when defining the attribute, seemed redundant to write the same explanation.

[domenic]

Looking good, just some polish work to do.

[khushalsagar]

Done, ready for another review.

[domenic]

I pushed a commit to fix the line wrapping. With that, this is good to go.

Also, please feel free to add your name to the acknowledgments section if you'd like!

[domenic]

All merged! Please file an MDN issue when you get the chance, and update the OP for posterity to link to it.