fix: Dispose canvas resources on graphics destroy

[fjwong]

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Description

Replaces canvas.clear() for canvas.dispose() in graphics.destroy().

• http:https://fabricjs.com/docs/fabric.Canvas.html#dispose
• http:https://fabricjs.com/docs/fabric.js.html#line11997)

I think this might be related to issues #375 and #395.

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[lja1018]

Reviewed.
Thank you for your PR.
This PR will probably add to v3.11.1

[stale]

This issue has been automatically marked as inactive because there hasn’t been much going on it lately. It is going to be closed after 7 days. Thanks!

[stale]

This issue will be closed due to inactivity. Thanks for your contribution!

[fjwong]

Hello, it seems this PR has been auto-closed.

I just want to ask, are there plans to merge this at some point? Right now I have to resort to doing some hacks on my application to address the out of memory issues that this PR intends to solve.