The library wasn't taken into account when handling computing class
members in the K/J-model and not handled correctly when computing
applicable selectors. This made dart2js unable to handle members with
a name private to a different library than the enclosing library.

Fixes #33732
Fixes #49226

Change-Id: I5ba143d87662bbd42e0ff02355054e4a937be8f8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/252665
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Stephen Adams <[email protected]>