[visualizer] use a different color based on the type of an audio node.

[hoch]

I implemented it like this:
https://github.com/hoch/canopy/blob/master/app/spiral-elements/spiral-audiograph/spiral-audiograph.html#L412

I wish there is a more structured way of doing this, but I don't think dagre supports it. Let's hack together. :)

[chihuahua]

Agreed. Passing style data like that sg. If only we could assign a CSS class to the node's SVG element.

[chihuahua]

Hey, we can add a CSS class to the node's SVG element (say destNode, sourceNode or midNode) and then vary panel.css. That lets us decouple styling logic from the JS.

[hoch]

Sounds good. This didn't work for Canopy because the svg element was in the Polymer Shadow DOM - but I am sure this will work for the extension.

[chihuahua]

I think we can say 0774ba4 took care of this issue.