Executing webview.eval during startup is inconsistent, the js code may or may not run.
We are discussing this issue on tauri [here](https://github.com/tauri-apps/tauri/issues/212). Test code below: expect 1000 `

` nodes to be added, but node 0 is not reliably inserted.

This was tested in 0.5.4 and 0.6.0. This may or may not be related to c++ async code handling [here](https://github.com/Boscop/web-view/blob/master/webview-sys/webview_edge.cpp#L308)

```rs
use web_view::*;

fn main() {
let webview = web_view::builder()
.title("Example")
.content(Content::Html(HTML))
.size(800, 600)
.resizable(true)
.debug(true)
.user_data(0)
.invoke_handler(|_webview, _arg| {
Ok(())
})
.build()
.unwrap();

let handle = webview.handle();
for i in 0..1000 {
handle.dispatch(move |webview| {
webview.eval(&format!("document.body.appendChild(document.createElement('p')).appendChild(document.createTextNode('Item {}'))", i))
}).unwrap();
}
webview.run().unwrap();
}

const HTML: &str = r#"

Hello World!

"#;
```

Reproduce the supplied Rust program with the EdgeHTML backend and check whether all 1,000 paragraph nodes are inserted during startup. Then inspect webview-sys/webview_edge.cpp around line 308, including the referenced C++ async handling; done means node 0 and the remaining nodes are inserted reliably.

Written by the indexing model from the issue text.