Merge pull request flutter#11 from dart-lang/pub-publish-1.8.0

Require at least SDK 1.8.0 because 'pub publish' demands this.

Author: scheglov

pubspec.yaml

@@ -5,7 +5,7 @@ author: Dart Team <[email protected]>
 homepage: https://github.com/dart-lang/test_reflective_loader
 
 environment:
-  sdk: '>=1.0.0 <2.0.0'
+  sdk: '>=1.8.0 <2.0.0'
 
 dependencies:
   test: ^0.12.0