Erroneous "No timeline event analysis data available for this frame"

I've only noticed this when running an app on debug-mode, not profile-mode

Steps to reproduce:

1. Open performance panel
2. Trigger some event in app that causes a lot of frames to be rendered (e.g. scrolling)
3. In the Frame chart, scroll to the beginning and click on one of the first frames ("Frame A")
4. See message: "No timeline event analysis data available for this frame."
5. Now scroll to the end of the frame chart, and start clicking on the frames there
6. Make your way back to "Frame A" and click on it again. The message is now gone.

Initial selection of frame:

Subsequent selection of frame:

在 Flutter DevTools 性能面板中使用 debug mode 和滚动等帧负载较高的操作重现该问题。比较在浏览后续帧之前和之后选择第一帧的情况；当初始帧能够显示其 Timeline 事件分析数据，且不需要选择其他帧时，即完成。

由索引模型根据 Issue 内容生成。