64584c128a
Moving variance to `js_shared/lib/variance.dart` so we can use the same synced indices when marking variance in both dart2js and ddc. This avoids needing to sync multiple data structures that all represent variance. Bug: https://github.com/dart-lang/sdk/issues/54367 Change-Id: Ia6fda84decd43374c08ed3bd0d0b240071310d9a Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/341840 Reviewed-by: Mayank Patke <fishythefish@google.com> Commit-Queue: Kallen Tu <kallentu@google.com> Reviewed-by: Nicholas Shahan <nshahan@google.com>
Package js_shared:
This code is a compile time dependency of dart2js and DDC. It is imported as
a package: import by both compilers.
There is an exact copy in the SDK of the libraries in the
pkg/js_shared/lib/synced sub-directory.
Those libraries are imported as dart: imports by the dart2js and DDC runtime
libraries.
Important: all code under pkg/js_shared/lib/synced must be kept in sync with
the runtime (in sdk/lib/_internal/js_shared/lib/synced) at all times. The
test/in_sync_test.dart test verifies this.