Selector: Use jQuery `:has` if `CSS.supports(selector(...))` non-compliant

jQuery has followed the following logic for selector handling for ages:
1. Modify the selector to adhere to scoping rules jQuery mandates.
2. Try `qSA` on the modified selector. If it succeeds, use the results.
3. If `qSA` threw an error, run the jQuery custom traversal instead.

It worked fine so far but now CSS has a concept of forgiving selector lists that
some selectors like `:is()` & `:has()` use. That means providing unrecognized
selectors as parameters to `:is()` & `:has()` no longer throws an error, it will
just return no results. That made browsers with native `:has()` support break
selectors using jQuery extensions inside, e.g. `:has(:contains("Item"))`.

Detecting support for selectors can also be done via:

```js
CSS.supports( "selector(SELECTOR_TO_BE_TESTED)" )
```
which returns a boolean. There was a recent spec change requiring this API to
always use non-forgiving parsing:
https://github.com/w3c/csswg-drafts/issues/7280#issuecomment-1143852187
However, no browsers have implemented this change so far.

To solve this, two changes are being made:
1. In browsers supports the new spec change to `CSS.supports( "selector()" )`,
   use it before trying `qSA`.
2. Otherwise, add `:has` to the buggy selectors list.

Fixes gh-5098
Closes gh-5107
Ref w3c/csswg-drafts#7676

1 files changed, 24 insertions, 0 deletions

diff --git a/src/selector/support.js b/src/selector/support.js
new file mode 100644
index 000000000..9763b0055
--- /dev/null
+++ b/src/selector/support.js
@@ -0,0 +1,24 @@
+import support from "../var/support.js";
+
+try {
+	/* eslint-disable no-undef */
+
+	// Support: Chrome 105+, Firefox 104+, Safari 15.4+
+	// Make sure forgiving mode is not used in `CSS.supports( "selector(...)" )`.
+	//
+	// `:is()` uses a forgiving selector list as an argument and is widely
+	// implemented, so it's a good one to test against.
+	support.cssSupportsSelector = CSS.supports( "selector(*)" ) &&
+
+		// `*` is needed as Safari & newer Chrome implemented something in between
+		// for `:has()` - it throws in `qSA` if it only contains an unsupported
+		// argument but multiple ones, one of which is supported, are fine.
+		// We want to play safe in case `:is()` gets the same treatment.
+		!CSS.supports( "selector(:is(*,:jqfake))" );
+
+	/* eslint-enable */
+} catch ( e ) {
+	support.cssSupportsSelector = false;
+}
+
+export default support;