Change a TODO to a permanent comment (dart-lang/stack_trace#114)

https://github.com/dart-lang/sdk/issues/19566 is closed and no changes
to the behavior are planned. Remove the TODO since this won't ever be
actionable, and change to an explanatory comment.
1 file changed
tree: b97668e59afd703a826b30c8d0f55cc2a6423ca8
  1. pkgs/