explicitly skip dart-ext: uris

[jakemac53]

At least partially fixes #2045

[natebosch]

Do you think we need to handle this in build_modules as well?

build/build_modules/lib/src/module_library.dart

Lines 81 to 85 in 11d1580

	if (uri.scheme == 'dart') {
	sdkDeps.add(uri.path);
	continue;
	}
	var linkedId = AssetId.resolve(path, from: id);

[jakemac53]

Do you think we need to handle this in build_modules as well?

Looks like we will need to yes, good catch

[jakemac53]

@natebosch pushed a commit to skip these uris during module creation as well, and filed #2047 to track native extension support (but there are no plans to actually work on that unless we have customers for it)