Allow nullsafety version(s) of bazel_worker (dart-lang#2990)

Allow nullsafety version(s) of bazel_worker (dart-lang#2990)

Allow the null safety release of pkg:html (dart-lang#2988)

udpate build_web_compilers pubspec version

udpate build_web_compilers pubspec version (dart-lang#2987)

Fix AssetId.resolve for empty uris (dart-lang#2985)

An empty uri resolves to whatever it's resolved against, but AssetId.resolve would resolve it to its parent.

Closes dart-lang#2984.

Fix AssetId.resolve for empty uris (dart-lang#2985)

An empty uri resolves to whatever it's resolved against, but AssetId.resolve would resolve it to its parent.

Closes dart-lang#2984.

Fix AssetId.resolve for empty uris (dart-lang#2985)

An empty uri resolves to whatever it's resolved against, but AssetId.resolve would resolve it to its parent.

Closes dart-lang#2984.

Fix AssetId.resolve for empty uris (dart-lang#2985)

An empty uri resolves to whatever it's resolved against, but AssetId.resolve would resolve it to its parent.

Closes dart-lang#2984.

Fix AssetId.resolve for empty uris (dart-lang#2985)

An empty uri resolves to whatever it's resolved against, but AssetId.resolve would resolve it to its parent.

Closes dart-lang#2984.