Alternate dimension bindings

[PlkMarudny]

Do you think this using this https://github.com/bluwy/svelte-fast-dimension package could have a positive impact on performance?

[GeoffCox]

@PlkMarudny Very interesting. The iframe technique does feel heavy. A ResizeObserver-based measurement might be much faster. I think you should propose this to sveltejs. I want to try and have zero dependencies for this component if possible.