Inject script doesn't work with auto-run feature

[johnpryan]

There's a timing issue where using the data-run / run=true feature will correctly auto-run, but doesn't run the right code. Instead of running the injected code, it runs whatever main.dart was created by default.

DartPad probably needs to know that it is waiting on an injected script, and then wait for that code before triggering the auto-run feature.

cc: @parlough @tugorez

[tugorez]

This is awesome, thanks both @johnpryan and @parlough :D!

I was playing with data-run="true" and found that although it actually auto renders the UI it seems I'm still able to see the default program for a second.

dartpad_autorun.webm

[parlough]

Yeah. I'm not sure how to avoid that 100% of the time without requiring a special flag to indicate not to run the initial script or gist. I might be able to adjust the order a bit and avoid running the initial script if a message was received from the embedder. I'll play around a bit.

[devoncarew]

@tugorez - I believe you're experimenting with re-mixing the dartpad UI a bit?

Instead of hosting the embedded view in a page, you might also consider forking and modifying the dartpad UI directly? As a Flutter web app, the UI components are reasonably modular, and it should be pretty quick to experiment with.