Window.requestFilesystem() call produces an error on dartdevk waek

[sgrekhov]

The following code produces an error on dartdevk-weak-linux-release-chrome configuration

import "dart:html";
main() async {
  Window nw = window;
  var fs = await nw.requestFileSystem(10);
}

Error message is not informative and looks like

Runtime window.onerror:
window.onerror called:

http://127.0.0.1:44241/root_build/gen/utils/dartdevc/kernel/amd/dart_sdk.js:4044:
Uncaught Error

Deobfuscated error and stack:
<no error message found>
    at window.onerror called:  unparsed
    at <fn>                    out/ReleaseX64/gen/utils/dartdevc/kernel/amd/dart_sdk.js 4044
    at Uncaught Error          unparsed

This code works well on dart2js configuration

Tested on the edge version of SDK (2.12)

[nshahan]

@rakudrama @srujzs This doesn't look like a well supported API https://developer.mozilla.org/en-US/docs/Web/API/Window/requestFileSystem. Do you think it should be removed or should we fix the DDC implementation?

[srujzs]

The DDC implementation fails for the same reason as some of the various ones around trying to modify the Object prototype e.g. Gamepad. The type DOMFileSystem is hidden and does not show up at the top level, so DDC cannot attempt to register the type. Dart2JS doesn't have this problem since it uses toString to determine the Native type.

We talked briefly about this, but I think it makes sense to just keep it as is and encourage users to use interop instead. It's deprecated, and the effort to handle this issue and similar issues in DDC will come with tradeoffs e.g. performance. At the same time, I don't think it makes sense to break users by removing it if they are using it.

There's also a few tests that depend on this to test the File APIs. I think they should be migrated to use interop as well at some point (maybe once we have static interop classes). From an initial pass, these include:

html/fileapi_file_test
html/file_sample_test
html/fileapi_file_entry_test
html/fileapi_directory_test
html/fileapi_supported_test
html/fileapi_directory_reader_test
html/fileapi_supported_throws_test.dart
html/callback_list_test.dart