This is a speculative fix that moves "background pages cleanup"
to `_didCloseInternal` so that it is only run once, but on both
context closure and browser closure.
Symptom from a flaky test:
```log
browserContext.close: page@18087c372d32819222707ca5e8fd1030 is sending "close" event after being disposed
at PageDispatcher._dispatchEvent (D:\a\playwright\playwright\src\dispatchers\dispatcher.ts:86:15)
at Page.<anonymous> (D:\a\playwright\playwright\src\dispatchers\pageDispatcher.ts:59:12)
at Page.emit (events.js:314:20)
at Page._didClose (D:\a\playwright\playwright\src\server\page.ts:220:10)
at CRPage.didClose (D:\a\playwright\playwright\src\server\chromium\crPage.ts:165:16)
at CRBrowserContext._onClosePersistent (D:\a\playwright\playwright\src\server\chromium\crBrowser.ts:476:24)
at CRBrowserContext.close (D:\a\playwright\playwright\src\server\browserContext.ts:288:20)
```
|
||
|---|---|---|
| .. | ||
| protocol.ts | ||
| webkit.ts | ||
| wkAccessibility.ts | ||
| wkBrowser.ts | ||
| wkConnection.ts | ||
| wkExecutionContext.ts | ||
| wkInput.ts | ||
| wkInterceptableRequest.ts | ||
| wkPage.ts | ||
| wkProvisionalPage.ts | ||
| wkWorkers.ts | ||