When adding imports for elements, we could leave unnecessary imports because the first element is imported through one library, and then a subsequent element is imported through a library that _also_ includes the first element.
With this change, any time we add a new element import, we will check the existing pending imports to see if any of those can be satisfied by this new import, and if so map it over and check whether the old import is now unused by any element imports (and not an explicit import), in which case it can be removed.
Fixes https://github.com/dart-lang/sdk/issues/56627
Change-Id: I82b638dfd2a36a72e5c7c55cae73842907ea3896
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/384780
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Danny Tuppeny
a79ab854f0