Unable to use js for prop values like attribute values

[okmanideep]

👇 works - ✅

<tags :value="tags.join(',')"></tags>

But 👇 does work - ❌

<tags @value="tags.join(',')"></tags>

While we are at it, it will be great if we can pass non strings as props, so we can just do this. Since props are just private to the webc runtime, this should not lead to any issues in the output.

<tags @value="tags"></tags>

[zachleat]

WebC v0.9.0 will feature a new :@ prefix (e.g. :@value="tags.join(',')") for dynamic properties, thank you!