Remove unnecessary braces in a string interpolation
Remove unnecessary braces in a string interpolation

Change-Id: I16d86df473e054a5f17b6c72f155467618ef0307
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/146823
Auto-Submit: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Reviewed-by: Keerti Parthasarathy <50d1d8bfaf73a210aebf5aef847d5b7b93955336@google.com>
Commit-Queue: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk