[BUG] Locator.count() with _vue selector with Repro

[yuvalkarif]

Context:

• Playwright Version: 1.19.2
• Operating System: Windows
• Node.js version: v16.13.0
• Browser: Chromium
• Nuxt: 2.15.8
• Vue: 2.6.14

#12623

Managed to create a repro in this basic Nuxt project repo.
Simply created three Vue components, using a Locator with _vue selector I try to log their count and the output is indeed 0.
expect.toHaveCount() still works as intended.

[mxschmitt]

I can repro:

diff --git a/tests/page/selectors-vue.spec.ts b/tests/page/selectors-vue.spec.ts
index 239632404..6f47ad518 100644
--- a/tests/page/selectors-vue.spec.ts
+++ b/tests/page/selectors-vue.spec.ts
@@ -30,10 +30,12 @@ for (const [name, url] of Object.entries(vues)) {
 
     it('should work with single-root elements @smoke', async ({ page }) => {
       expect(await page.$$eval(`_vue=book-list`, els => els.length)).toBe(1);
+      expect(await page.locator(`_vue=book-list`).count()).toBe(1);
       expect(await page.$$eval(`_vue=book-item`, els => els.length)).toBe(3);
+      expect(await page.locator(`_vue=book-item`).count()).toBe(3);
       expect(await page.$$eval(`_vue=book-list >> _vue=book-item`, els => els.length)).toBe(3);
+      expect(await page.locator(`_vue=book-list >> _vue=book-item`).count()).toBe(3);
       expect(await page.$$eval(`_vue=book-item >> _vue=book-list`, els => els.length)).toBe(0);
     });
 
     it('should work with multi-root elements (fragments)', async ({ page }) => {

Reason is probably that toHaveCount is using the main world and in locator.count() we are using the utility context.

Relates #11256