In ScopeResolverVisitor, don't visit identifiers to the right of `.`.
In ScopeResolverVisitor, don't visit identifiers to the right of `.`.

There's no need to visit these identifiers because they aren't looked
up using the current scope.  Previously, we avoided doing these
lookups by doing some `is` and `identical` checks in
visitSimpleIdentifier, but it's more efficient (and more
straightforward) to simply avoid visiting the identifiers altogether.

Change-Id: Ibea28e196b206d88f5ad765d3d64a24c7b0e7d5e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/209855
Reviewed-by: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk