machines: Fix VNC display exceptions
machines: Fix VNC display exceptions

VNC just plain doesn't work on my machine. In addition it causes
errors in the tests. This commit should fix the following issues

 * ReferenceError: Can't find variable: WebUtil
 * TypeError: message: novncContainer is undefined
 * TypeError: toBeVisibleRow is undefined

Closes #7387
larsu/cockpit,SotolitoLabs/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,michalskrivanek/cockpit,mareklibra/cockpit,stefwalter/cockpit,harishanand95/cockpit,cockpituous/cockpit,michalskrivanek/cockpit,xhad/cockpit,SotolitoLabs/cockpit,michalskrivanek/cockpit,moraleslazaro/cockpit,petervo/cockpit,SotolitoLabs/cockpit,larskarlitski/cockpit,Scribery/cockpit,garrett/cockpit,michalskrivanek/cockpit,larsu/cockpit,stefwalter/cockpit,stefwalter/cockpit,garrett/cockpit,larskarlitski/cockpit,harishanand95/cockpit,mareklibra/cockpit,deryni/cockpit,martinpitt/cockpit,Scribery/cockpit,harishanand95/cockpit,mvollmer/cockpit,larsu/cockpit,deryni/cockpit,cockpituous/cockpit,michalskrivanek/cockpit,andreasn/cockpit,Scribery/cockpit,petervo/cockpit,mareklibra/cockpit,cockpituous/cockpit,harishanand95/cockpit,larsu/cockpit,mvollmer/cockpit,garrett/cockpit,xhad/cockpit,andreasn/cockpit,SotolitoLabs/cockpit,martinpitt/cockpit,harishanand95/cockpit,cockpituous/cockpit,xhad/cockpit,xhad/cockpit,cockpit-project/cockpit,martinpitt/cockpit,andreasn/cockpit,andreasn/cockpit,cockpit-project/cockpit,harishanand95/cockpit,xhad/cockpit,garrett/cockpit,deryni/cockpit,andreasn/cockpit,deryni/cockpit,andreasn/cockpit,Scribery/cockpit,mareklibra/cockpit,stefwalter/cockpit,martinpitt/cockpit,stefwalter/cockpit,andreasn/cockpit,xhad/cockpit,moraleslazaro/cockpit,harishanand95/cockpit,SotolitoLabs/cockpit,larsu/cockpit,cockpit-project/cockpit,deryni/cockpit,larskarlitski/cockpit,stefwalter/cockpit,michalskrivanek/cockpit,mvollmer/cockpit,xhad/cockpit,cockpit-project/cockpit,larskarlitski/cockpit,larskarlitski/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,petervo/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,larsu/cockpit,deryni/cockpit,SotolitoLabs/cockpit,deryni/cockpit,petervo/cockpit,larskarlitski/cockpit,mareklibra/cockpit,michalskrivanek/cockpit,petervo/cockpit,Scribery/cockpit,mareklibra/cockpit,Scribery/cockpit,stefwalter/cockpit,Scribery/cockpit,moraleslazaro/cockpit,larskarlitski/cockpit,petervo/cockpit,cockpituous/cockpit,SotolitoLabs/cockpit,cockpit-project/cockpit,petervo/cockpit,garrett/cockpit,mareklibra/cockpit,cockpituous/cockpit