VM and Dartium don't respect @lazy and DeferredLibrary

[DartBot]

This issue was originally filed by @sethladd

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Consider this code:

import 'dart:html';
import 'dart:async';

@lazy
import 'reverser.dart';

const lazy = const DeferredLibrary('reverser', uri: './part.js');

void main() {
  print('in main');
  new Timer(const Duration(seconds:3), () {
    lazy.load().then((_) {
      print('library loaded');
      query("#sample_text_id")
        ..text = "Click me!"
        ..onClick.listen(reverseText);
    });
  });
}

void reverseText(MouseEvent event) {
  query("#sample_text_id").text = reverse(query("#sample_text_id").text);
}

In the network panel of Dev Tools, I see the request for reverser.dart immediately on page load. I was expecting now to see the request until after the Timer fires.

[DartBot]

This comment was originally written by @mhausner

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Is there an agreed upon spec that defines semantics of annotations that the VM has to recognize and follow?

[DartBot]

This comment was originally written by ventura....@gmail.com

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This seams like a very important performance feature that must be included in the vm and dartium. Could this also applies to html imports? I have followed the posts from ilya grigorik about 1 second load times for web pages and js deferring and other code loading is fundamental so i dont see any reason not to do it on the vm. I hope it comes soon to the vm also

[kasperl]

We haven't really discussed this in details yet. It isn't clear what the VM is supposed to do -- I think dart2dart translation might be a part of the answer here.

Changing to an "enhancement request".

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cc @peter-ahe-google.
Removed Type-Defect label.
Added Type-Enhancement, Area-VM, Triaged labels.

[iposva-google]

As Kasper said in comment 3, so far this has been discussed a deployment feature which you will get with dart2dart. The VMs involvement in supporting this ends with giving the dart2dart generated code access to loading sources lazily through a library call. This library API still needs to be specified though.

[iposva-google]

Removed Priority-Medium label.
Added Priority-Unassigned label.

[sethladd]

Added AssumedStale label.