fix: remove incorrect special handling of :export pseudo-selectors (#18839)

#18793 added special handling for `:export` selectors, but this is
incorrect. `:export` is (apparently) part of [Interoperable
CSS](https://github.com/css-modules/icss) but Svelte doesn't (and
shouldn't) know what that is. No changeset because #18793 is unreleased,
and the changeset in that PR didn't mention ICSS

packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js

@@ -146,16 +146,9 @@ export function prune(stylesheet, elements) {
 		ComplexSelector(node) {
 			const selectors = get_relative_selectors(node);
 			const rule = /** @type {Compiler.AST.CSS.Rule} */ (node.metadata.rule);
-			const first = selectors[0]?.selectors[0];
-			const is_icss_export =
-				selectors.length === 1 &&
-				selectors[0].selectors.length === 1 &&
-				first?.type === 'PseudoClassSelector' &&
-				first.name === 'export' &&
-				first.args === null;
 
 			// Global and ICSS export rules do not depend on an element in this component
-			if (every_is_global(selectors, 0, selectors.length, rule) || is_icss_export) {
+			if (every_is_global(selectors, 0, selectors.length, rule)) {
 				node.metadata.used = true;
 			}
 

packages/svelte/tests/css/samples/global-head-only/expected.css

@@ -1,2 +1 @@
-:export { foo: red; }
 	:is(td, th) { color: red; }

packages/svelte/tests/css/samples/global-head-only/input.svelte

@@ -1,6 +1,5 @@
 <svelte:head><meta name="x" content="y" /></svelte:head>
 
 <style>
-	:export { foo: red; }
 	:is(:global(td), :global(th)) { color: red; }
 </style>