If `identifiers` is empty it means we didn't collect any right now, not that there weren't any to be collected. We should only stop the timer if `collectedAllRemoteRenderingBuffers` is true (as well as `successfullyMadeBackingStoreVolatile`).
<rdar://problem/119344111>
Pull request: https://github.com/WebKit/WebKit/pull/21477
Committed 271704@main (052b3e14ae00): <https://commits.webkit.org/271704@main> Reviewed commits have been landed. Closing PR #21477 and removing active labels.