chore: don't leak from waitFor (#22465)

Fixes https://github.com/microsoft/playwright/issues/22458

package-lock.json

@@ -6199,6 +6199,7 @@
       }
     },
     "packages/playwright-ct-core": {
+      "name": "@playwright/experimental-ct-core",
       "version": "1.33.0-next",
       "license": "Apache-2.0",
       "dependencies": {

packages/playwright-core/src/server/frames.ts

@@ -815,6 +815,10 @@ export class Frame extends SdkObject {
           result.dispose();
           return continuePolling;
         }
+        if (options.omitReturnValue) {
+          result.dispose();
+          return null;
+        }
         const element = state === 'attached' || state === 'visible' ? await result.evaluateHandle(r => r.element) : null;
         result.dispose();
         if (!element)

packages/playwright-core/src/server/types.ts

@@ -25,7 +25,7 @@ export type StrictOptions = {
 
 export type QueryOnSelectorOptions = StrictOptions & TimeoutOptions;
 
-export type WaitForElementOptions = TimeoutOptions & StrictOptions & { state?: 'attached' | 'detached' | 'visible' | 'hidden' };
+export type WaitForElementOptions = TimeoutOptions & StrictOptions & { state?: 'attached' | 'detached' | 'visible' | 'hidden' } & { omitReturnValue?: boolean };
 
 export type WaitForFunctionOptions = TimeoutOptions & { pollingInterval?: number };
 

tests/page/page-leaks.spec.ts

@@ -149,3 +149,33 @@ test('expect should not leak', async ({ page, mode, browserName, toImpl }) => {
     expect(counts.main + counts.utility).toBeLessThan(25);
   }
 });
+
+test('waitFor should not leak', async ({ page, mode, browserName, toImpl }) => {
+  test.skip(mode !== 'default');
+
+  await page.setContent(`
+    <button>static button 1</button>
+    <button>static button 2</button>
+    <div id="buttons"></div>
+  `);
+
+  for (let i = 0; i < 25; ++i) {
+    await page.evaluate(i => {
+      const element = document.createElement('button');
+      element.textContent = 'dynamic ' + i;
+      document.getElementById('buttons').appendChild(element);
+    }, i);
+    await page.locator('#buttons > button').waitFor();
+    await page.evaluate(() => {
+      document.getElementById('buttons').textContent = '';
+    });
+  }
+
+  expect(leakedJSHandles()).toBeFalsy();
+
+  if (browserName === 'chromium') {
+    const counts = await objectCounts(toImpl(page), 'HTMLButtonElement');
+    expect(counts.main + counts.utility).toBeGreaterThanOrEqual(2);
+    expect(counts.main + counts.utility).toBeLessThan(25);
+  }
+});