The `sdkRoot` argument to start is not honoured everywhere

[nielsenko]

Notice how in lib/src/frontend_server_client.dart:

final _dartAotRuntimePath = p.join(sdkDir, 'bin', 'dartaotruntime');

final _feServerAppJitSnapshotPath =
    p.join(sdkDir, 'bin', 'snapshots', 'frontend_server.dart.snapshot');

final _feServerAotSnapshotPath =
    p.join(sdkDir, 'bin', 'snapshots', 'frontend_server_aot.dart.snapshot');

just use sdkDir which is set in lib/src/shared.dart

final sdkDir = p.dirname(p.dirname(Platform.resolvedExecutable));

Problem is that Platform.resolvedExecutable doesn't work with dart install.

However

  static Future<FrontendServerClient> start(
    ...
    String? sdkRoot, // Defaults to the current SDK root.
  })

if only it was used correctly, like:

String _dartAotRuntimePath(String? sdkRoot) =>
    p.join(sdkRoot ?? sdkDir, 'bin', 'dartaotruntime');

String _feServerAppJitSnapshotPath(String? sdkRoot) => p.join(
    sdkRoot ?? sdkDir, 'bin', 'snapshots', 'frontend_server.dart.snapshot');

String _feServerAotSnapshotPath(String? sdkRoot) => p.join(
    sdkRoot ?? sdkDir, 'bin', 'snapshots', 'frontend_server_aot.dart.snapshot');

then it would work with dart install as well, if we pass the sdkRoot argument.

[srujzs]

This may be semi-related: #2758 but it could also be related to other issues we've had around finding the Dart binary/libraries (e.g. #2698).