Merge pull request #100 from dart-lang/sdk_constraint

Fixed SDK constraint [TBR].
diff --git a/pubspec.yaml b/pubspec.yaml
index 63b3a84..91788cf 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,6 +3,8 @@
 author: Dart Team <misc@dartlang.org>
 description: Style linter for Dart.
 homepage: https://github.com/dart-lang/linter
+environment:
+  sdk: '>=1.8.0 <2.0.0'
 dependencies:
   analyzer: ^0.25.0-dev.1
   args: '>=0.12.1 <0.14.0'