css: CSSStyleSheet.replace() should resolve to the stylesheet

src/browser/tests/css/stylesheet.html

@@ -492,7 +492,8 @@
 
     let replacedAsync = false;
     testing.async(async () => {
-        await sheet.replace('.async-test { margin: 10px; }');
+        const result = await sheet.replace('.async-test { margin: 10px; }');
+        testing.expectTrue(result === sheet);
         testing.expectEqual(1, sheet.cssRules.length);
         testing.expectEqual('.async-test', sheet.cssRules[0].selectorText);
         replacedAsync = true;

src/browser/webapi/css/CSSStyleSheet.zig

@@ -79,7 +79,7 @@ pub fn deleteRule(self: *CSSStyleSheet, index: u32, page: *Page) !void {
 
 pub fn replace(self: *CSSStyleSheet, text: []const u8, page: *Page) !js.Promise {
     try self.replaceSync(text, page);
-    return page.js.local.?.resolvePromise({});
+    return page.js.local.?.resolvePromise(self);
 }
 
 pub fn replaceSync(self: *CSSStyleSheet, text: []const u8, page: *Page) !void {