tree 3edc9db989798f6047fad175aba9b8fb85650cb0
parent 1cad08d3ee7b14e00fee83718236b92e5cf9c9e9
author Andreas Kirsch <blackhc@google.com> 1421107227 -0800
committer Natalie Weizenbaum <nweiz@google.com> 1421107227 -0800

Rewrite isEmpty and isNotEmpty to just access the isEmpty/isNotEmpty.

Adapt the unit tests and add a small regression test for
https://code.google.com/p/dart/issues/detail?id=21562 to check that
`expect(null, isNot(isEmpty))` fails.

BUG=21792, 21562