Suspected memory leak

### Bug Description:

While working on the `pixi.js-legacy` upgrade (#317 ), I noticed `Jest` reporting a potential memory leak:


I investigated using the `theia-trace-extension` example application, producing heap snapshots, and noticed that opening and closing trace views / trace experiments, results in an evrer-growing heap usage (even after manually triggering garbage collection).

See below for a screen capture - a "diff" between two heap snapshots, between which I opened and closes several trace views. The "detached" DOM objects seem to be related to timeline chart / pixi (e.g. WebGL canvas):


### Steps to Reproduce:

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### Additional Information

- Operating System: