Based on abandoned change #264261.
Changes to that PR: compare and show file paths, improve part parsing, include analyzer expectations from other files as well as CFE expectations, update unit tests.
Add end to end tests. The simplest case "library_failure_test.dart" passes before this PR, all others require the change in this PR to pick up expectations in other files.
Change-Id: Ia71b78a8f0dced83f603309877132f261b47c5a3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/345541
Reviewed-by: Erik Ernst <eernst@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>
Commit-Queue: Morgan :) <davidmorgan@google.com>
David Morgan