[selectors-4] Case-sensitive attribute selectors #2101

The Selectors spec says:

By default case-sensitivity of attribute names and values in selectors depends on the document language. To match attribute values case-insensitively regardless of document language rules, the attribute selector may include the identifier i before the closing bracket (]).

Could there be a similar flag for case-sensitive matching?

I needed to select <ol> with type=a or type=A and apply different styles to them.

@counter-style list-a {
    system: extends lower-alpha;
    suffix: ') ';
}

@counter-style list-A {
    system: extends upper-alpha;
    suffix: ') ';
}

ol[type=a] {
    list-style: list-a;
}

ol[type=A] {
    list-style: list-A;
}

<ol type="a">
    <li>foo</li>
    <li>bar</li>
    <li>baz</li>
</ol>

<ol type="A">
    <li>foo</li>
    <li>bar</li>
    <li>baz</li>
</ol>

The desirable result is:

a) foo
b) bar
c) baz

A) foo
B) bar
C) baz

But this doesn’t work because browsers match type attributes case-insensitively, so the second style rule overwrites the first one.

Thus the actual result is:

A) foo
B) bar
C) baz

A) foo
B) bar
C) baz