[blink-dev] Intent to Deprecate and Remove: CSSUnknownRule

[Sunil Ratnu]

Contact emails
sunil...@samsung.com

Summary
Remove the CSSUnknownRule interface. The CSSUnknownRule interface represents an at-rule not supported by this user agent.

Motivation
The CSSUnknownRule interface was introduced in DOM Level 2 Style, but has been removed in CSSOM:
http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSUnknownRule
http://dev.w3.org/csswg/cssom/

Compatibility Risk
Low.

Usage information from UseCounter
This cannot be meaningfully measured with use counters, because the interface object is an attribute on the window object, so e.g. enumerating the attributes on window would trigger the use counter.

Entry on chromestatus.com, crbug.com, or MDN
https://code.google.com/p/chromium/issues/detail?id=496383

Requesting approval to remove too?
Yes.

[Elliott Sprehn]

You could use counter how often we create a wrapper for one of these instances. That said this seems pretty low risk. The OM for sheets and rules have very low usage in general.

[Philip Jägenstedt]

LGTM!

Which template did you use for this email? The one in
http://www.chromium.org/blink#launch-process has been changed to
include "Entry on the feature dashboard" so if there's another it
needs to be updated. Anyway, I created an entry for you that assumes
that this will be removed in M45:
https://www.chromestatus.com/features/4693141533753344

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[Philip Jägenstedt]

I hope I'm not mistaken, but in the bug I wrote "It is never created
internally, so the only consequence of removing it is that the
CSSUnknownRule interface object itself will go away."

[Philip Jägenstedt]

Another thing I think should be included in this Intent to Remove is the constant CSSRule.UNKNOWN_RULE, as it's also gone from the spec and there will never be a CSSRule object where rule.type==CSSRule.UNKNOWN_RULE.

[Sunil Ratnu]

@Philip: Thank you for creating the entry on the feature dashboard. I did download the latest template from http://www.chromium.org/blink#launch-process but I already had a template downloaded previously and somehow ended up using the previous one. The link does have the updated template.

@Elliott and @Philip: Since this already seems low risk, could you please provide your final thoughts on whether we should go for the use counters first and then go for the removal?  Also I will go for the removal of  CSSRule.UNKNOWN_RULE once we have the consensus for it as well.

[Elliott Sprehn]

This is obscure enough I'd say just remove it and wait to see what breaks (probably nothing).

[Philip Jägenstedt]

I agree that there's no need to add use counters here, and since the CSSUnknownRule interface object is on window that counter would be hit by generic enumeration.

Let's treat CSSUnknownRule and CSSRule.UNKNOWN_RULE as a group, and remove them together if/when you get two more LGTMs.

[Dimitri Glazkov]

LGTM2.

:DG<

[Chris Harrelson]

LGTM3