Change AnalysisContext.analysisOptions setter to just remembering the AnalysisOptions object.
Change AnalysisContext.analysisOptions setter to just remembering the AnalysisOptions object.

There was a bug with not copying enabledExperiments.

We don't do such defensive copying for other objects.

R=1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com, paulberry@google.com

Change-Id: I4508b8101d9a912e1645932a3f9c1855f71969c4
Reviewed-on: https://dart-review.googlesource.com/c/88740
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Commit-Queue: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

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