Actually limit number of stored exception contexts.
Actually limit number of stored exception contexts.

R=brianwilkerson@google.com
BUG=

Review-Url: https://codereview.chromium.org/2666003002 .

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