CircularFunctionTypeImpl does not have element.
CircularFunctionTypeImpl does not have element.

The previous implementation attempted to cast DynamicElementImpl
to FunctionElement.

R=1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com, 72d414e3a99fb120308437779d51667bcc0984eb@google.com

Bug:
Change-Id: I6cb7d11419ea463313d4a86c3a0412998168ec85
Reviewed-on: https://dart-review.googlesource.com/5060
Reviewed-by: Paul Berry <72d414e3a99fb120308437779d51667bcc0984eb@google.com>
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Commit-Queue: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

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