Interpolation in multiple class tags only works after hotreload

**Problem**

Multiple `class` tag concatenation doesn't seem to work at load, if one of the `class` tags contains an interpolated variable.

**Steps To Reproduce**

The following works as expected
```rs
#[component]
fn Thing(more_class: &'static str) -> Element {
rsx! {
div { class: "flex {more_class}",
"text"
}
}
}
```

The following has generated `class` empty on load after full rebuild or just launching the executable
```rs
#[component]
fn Thing(more_class: &'static str) -> Element {
rsx! {
div { class: "flex", // a lot of other classes on the same line
class: "{more_class}", // hence the multiple class tags which usually get concatenated
"text"
}
}
}
```
generates : `