style nodes get processed twice

[hrj]

Our HTML parser first appends the style node to the DOM, then appends its child nodes to the style node.

The style node gets an "attached-to-DOM" event and then a "child-list-changed" event. This causes the CSS to be parsed twice.

The simplest fix for this would be to detect the case of missing child-nodes and create an empty stylesheet directly.

A more sophisticated solution would avoid any duplicate processing. For eample, by inform the style node that parsing is incomplete when it is first attached to the DOM.