859e359266
Add `RequestChannelException`, remove unused `RemoteExcepion`, update some doc comments. R=jakemac@google.com Change-Id: Id51d2a9d16e7d4599703470b5c974c2bd438c55e Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/352911 Auto-Submit: Morgan :) <davidmorgan@google.com> Reviewed-by: Johnni Winther <johnniwinther@google.com> Commit-Queue: Johnni Winther <johnniwinther@google.com> Reviewed-by: Konstantin Shcheglov <scheglov@google.com>