fromExistingSession function
        
Future<WebDriver> 
fromExistingSession(
    
- String sessionId, {
- Uri? uri,
- WebDriverSpec spec = WebDriverSpec.Auto,
Creates an async WebDriver from existing session using AsyncXhrRequestClient.
This will bring in dependency on dart:html.
Note: WebDriver endpoints will be constructed using resolve against
uri. Therefore, if uri does not end with a trailing slash, the
last path component will be dropped.
Implementation
Future<core.WebDriver> fromExistingSession(String sessionId,
        {Uri? uri, WebDriverSpec spec = WebDriverSpec.Auto}) =>
    core.fromExistingSession(AsyncXhrRequestClient.new, sessionId,
        uri: uri, spec: spec);