Draco: Update globalThis definitions in Draco modules

[alexchuber]

globalThis can be undefined in a Native environment. (Why? I do not know yet :) ) In the meantime, this PR replaces it with the ancient, pre-ES2020 way of getting the global object.

[bjsplat]

Please make sure to label your PR with "bug", "new feature" or "breaking change" label(s).
To prevent this PR from going to the changelog marked it with the "skip changelog" label.

[bjsplat]

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[bjsplat]

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[bjsplat]

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[bjsplat]

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[bjsplat]

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[sebavan]

Blindly trusting you on this one :-)