Issue 34546. Get ClassElementImpl a way that support element handles.
Issue 34546. Get ClassElementImpl a way that support element handles.

R=1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com

Bug: https://github.com/dart-lang/sdk/issues/34546
Change-Id: Ib14afd83db49cbcd3b9a5d6832689dec9dfd5c57
Reviewed-on: https://dart-review.googlesource.com/75986
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Commit-Queue: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk