Don't assume DOM hasn't been loaded yet

[jiri-janousek]

This isn't guaranteed and it leads to an incompatibility with Nuvola Player 3.0.3 which emits InitWebWorker signal when DOM document is ready already.

• Author: Jiří Janoušek janousek.jiri@gmail.com
• Reviewed by: FIXME

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[SteVwonder]

Code change looks good. I'll test it out later this evening.