Steps to reproduce:
1. Load Web Inspector on about:blank
2. Navigate to acko.net
3. Wait for the initial animation to finish
=> Canvas 1 disappears from overview, but still has a path component
This reproduced most times for me. It's really confusing. If the canvas got GC'd maybe we should not show it in the overview, but still list it in the navigation sidebar and gray it out? I think we try to do something similar (or have considered doing so) for resources that have been discarded or GC'd. Blob resources are a good example of this.
Is this still an issue? I think it might've gotten fixed in <https://webkit.org/b/178806> Web Inspector: Canvas Tab: canvas path components from old page stick around when page is reloaded
Does not seem to repro any more. Now that we have back traces.. it seems that the first canvas is simply used for feature detection and gets GC'd at an arbitrary point.