Paragraph of placeholder attribute on input element
https://html.spec.whatwg.org/multipage/input.html#the-placeholder-attribute

If a user agent normally doesn't show this hint to the user when the control is focused, then the user agent should nonetheless show the hint for the control if it was focused as a result of the autofocus attribute, since in that case the user will not have had an

https://aomediacodec.github.io/av1-avif/#avif-mime-definition

.avif image/avif
.avifs image/avif-sequence

This is being prototyped in Chrome: https://bugs.chromium.org/p/chromium/issues/detail?id=960620

Presumably these should result in a network error. The current specification doesn't state anything and it's not tested either.

See the README for instructions on where to add tests. In the specification the "blob" case of https://fetch.spec.whatwg.org/#scheme-fetch needs updating to handle current URL’s blob URL entry being null.

Under point 6 of the list of steps to take to "ensure pre-insertion validity", as part of an attempt to implement a procedure involving the particular list of steps, I am having trouble unambiguously interpreting the following statement:

parent has an element child, child is a doctype, or child is non-null and a do

Ack, will do after we finalize the WiFi support

Originally posted by @yufengwangca in project-chip/connectedhomeip#1909 (comment)

What should be the result of new url("#")?
Browsers return different results and It confuses me.

In my understanding is that new url("#") should throw a validation error.

1. scheme start state
   1. [skip] If c is an ASCII alpha, append c, lowercased, to buffer, and set state to scheme state.
   2. [match] Otherwise, if state over