b9045af57b
Lookup in the library import can be very slow and it is not needed
most of the time. This change makes Library::Lookup{Class,Function,Field}[AllowPrivate]
lookups local in the library and cleans up related or unused code.
TEST=ci
Change-Id: If5a99bce7d712ce3a898395f74d4febac0311048
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/323221
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>