[cssom] U+0000 does not need to be replaced when serializing an identifier

[cdoublev]

I think that U+0000 does not need to be replaced in serialize an identifier.

To serialize an identifier means to create a string represented by the concatenation of, for each character of the identifier:

• If the character is NULL (U+0000), then the REPLACEMENT CHARACTER (U+FFFD).
• [...]

The examples below the definition of CSS.escape() use it in document.querySelector() but this method parses its input with parse a selector, which leads to replacing U+0000 with U+FFFD in filter code points.

[Loirooriol]

I think Typed OM can avoid "filter code points":

var v = new CSSKeywordValue("a\u0000b");
v.value; // "a\u0000b"
v.toString(); // "a�b"

[cdoublev]

I think Typed OM can avoid "filter code points" [when creating new CSSKeywordValue("a\u0000b")]

I cannot find where it is defined in CSS Typed OM, that CSSKeywordValue.toString() uses serialize an identifier.

However I recently learned that CSSKeyframesRule.name is supposed to accept any non-empty input (#9363), unlike animation-name, which is restricted to custom idenfiers and strings, and CSSOM uses serialize an identifier to serialize CSSKeyframesRule.name while serializing CSSKeyframesRule.cssText.

The bottom line is that serialize an identifier also replaces U+0000, for convenience, to serialize a user input specified via JS and that was not parsed as a CSS value, therefore I am closing this issue.