Ah whoops, I didn't notice that, when Turbo morphs the
`<measured-container>` into what the server HTML returns, it deletes
the `style` attribute we were using.
In this change, I refactor for `MeasuredContainer` to be the component
rather than `MeasuredContent`, so that it can also be responsible for
listening for changes to its own `style` prop, and remeasuring when
they happen.
We're also careful to avoid infinite loops, by only doing this when the
property is missing! (Otherwise, setting `--natural-width` triggers the
callback again, oops!)
Emi Matchu
1f1c6d92b1