would be nice if we could choose the package path via config. Would that be possible here?

yeah can you include this into the bindings. it would be nice to provide an array of conventions.

bind(URL_CONFIG).toValue([
  { package: 'node',  url:'/node_modules/' },
  { package: 'bower', url:'/bower_components/' },
  { package: 'web',   url:'/web_modules/' }
])

Yes, please make this configurable via an OpaqueToken. Maybe use @Optional and throw if not set and packages is used, as I doubt that people really serve their node_modules folder in production...

Having never used bower (and not sure where web_modules are coming from, webpack?) I would not be able to verify that it works properly, so I'll punt on this here but I logged #3257 so we do not forget.

Could we not have this method here? I.e. the getOuterHTML for the browser_adapter.ts does not include this logic. Instead, a user should just do what you do in the implementation: DOM.getOuterHTML(document.documentElement), which works in Dart and JS

gone

If you make the UrlResolver configurable via a token, we don't need a custom UrlResolver for the demos at all!

leaving UrlResolver untouched, so this still makes sense.