WebGL: child nodes don't inherit their opacity from the parent node

[mikekucera]

Environment info

• Cytoscape.js version : 3.34.0-unstable
• Browser/Node.js & version : Node v20.19.2, Chrome 139

Current (buggy) behaviour

When in webgl mode, child nodes don't inherit their opacity from the parent node.

Desired behaviour

Should work the same as when in canvas mode.

Minimum steps to reproduce

I used the debug/webgl/index.html site. Change to the "Compound Nodes" network. Go to the network-compound-nodes.json file and set the parent selector opacity to 0.5. Compare how it looks when webgl is enabled vs disabled.

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